Update:

I've just come in from work and bitcoin core has fully synced and is now running as a node. The downloaded blockchain files have caused my small SSD to be half full but I don't mind. In fact, I've been thinking of buying a bigger SSD and the prices are reasonable right now for a decent sized one, so I might upgrade in the next couple of weeks.

After looking at this page it's surprised me how few nodes there are when you think how many people are prepared to invest big money in BTC without supporting the network. I'd urge more people to install bitcoin core and help out. The official link is at the top of the boards, under your user name.

You won't gain any BTC from it but you can do your bit to keep this dream alive.

Anyway, enough of the smug-ness. I'll be keeping my node running as often as possible as the main PC is on almost 24/7.

I wonder if criminal activity will be a contributing factor to devastation of life as we know it before fuels become an issue.

If bitcoin (or other crypto) becomes a world leading currency there will be a huge possibility for business between amoral beings. Should we be worried that police services will become powerless over criminals?

I doubt it, Angela.

It's taken 5 years for the blockchain to get to 20 GB. Imagine the average size of a home computers hard drive in 5 years time.

Just restarted and I'm down to 13 weeks now. 

In options, map port using UPnP is checked. Can I turn that off now that I've forwarded port 8333 in ufw?

It's usually, but not always, on for 24 hours, so I'll run a node.

The sync has slowed right down at 14 weeks to go, so I guess it's now catching up with data that wasn't in bootstrap.dat.

I've started ufw and I've opened up port 8333 using "sudo ufw allow 8333" whilst bitcoin-qt was running. I don't need to restart bitcoin-qt, do I? Will I lose all of my sync'ed data? I'm guessing it will just carry on where it left off, right?

Thanks. I started syncing and looked in my ~/.bitcoin/blocks directory and can see a load of blk00xxx.dat files being generated. Each one is 134.2MB and I was thinking that the client will use those once it's fully synced.

Currently about half way through sync and I will delete bootstrap.dat once it's finished.

BTW, Is it a good idea to leave bitcoin-qt running permanently as a node to help the bitcoin network when I'm not using it?

I asked a very similar question last month. This should help satisfy your reservations:

https://bitcointalk.org/index.php?topic=604002.msg6796461#msg6796461

I like to simplify it by thinking of the "needle in a haystack" scenario, whereby every time you remove a strand of hay it goes back on top of the pile. Combine that with natural human error (non-perfect vision, memory etc.) and you've got as much chance of finding someone’s private key as looking for a needle in a haystack.

Unless someone develops a super computer that is beyond our comprehension and/or uses a completely different system to any doped silicon transistor model we have today your private keys are safe if you follow safe procedures.

Is there a script that I could run in Linux for generating an address/private key combo?

I used an HTML copy of the bitaddress site last time on a fresh installation of linux.

I would be happier running a short script which is far easier to examine for any kind of malware. Preferably something which allows you to add an audio file as entropy, since I can generate that by using my little netbook's built in microphone and creating some background noise.   

I've set up bitcoin-qt on Ubuntu and have a copy of bootstrap.dat downloaded and I'm ready to sync.

When I copy bootstrap.dat to my ~/.bitcoin directory and start up the client I understand it will consolidate the data from bootstrap.dat to speed up sync of my client with the blockchain.

What I want to know is: will I end up with twice as much hard disk space missing once sync has finished?

I haven't got that much room left on this particular drive and I don't wanna lose 2 x 17GB = 34GB worth of space.

Ta.

If it does crash briefly I'll have no qualms about buying cheaply. I'm new to the investment game but I can't see a long term risk even if that means waiting 2+ years.

If the Richard Branson's and eBay CEO's of this world are starting to enter the game it's zeitgeist for sure.

I'd like to see greater development for less tech savvy people to walk around with easy to use smartphone wallets that pay on screen in dollars and do the BTC conversion seamlessly and I believe that's a natural development that will come soon. Who cares if us purists do the conversion ourselves, so long as BTC reaches the masses it can only be good for stability and gradual price boost.

Partially correct. If it has NEVER been connected to a network it should be safe. You're better off wiping the entire hard drive and installing a version of Linux (Lubuntu is a favourite of mine), then using it for generating a paper wallet address and private key. It must NEVER be connected to the internet for it to be safe, but if you rarely use it that shouldn't be a problem for you.

I've recently started to do cold storage and sometimes think "I could cash a little bit of one BTC out to pay for X,Y,Z" but the thought of what that little piece could equate to in future stops me from touching them. It sends you a bit obsessive, investing in BTC! 

Isn't it against the law to profit from drugs/money seized from criminal activity?

Shouldn't the coins be burned (i.e. private keys wiped forever) or are the proceeds from this sale going to good use, such as an addiction charity?

The cops are legally obliged to incinerate drugs and drug money, aren't they?

I'm not getting on some kind of moral high horse, here. I was a member of Silk Road back in the day but it doesn't seem right that they would gain from this.

Thanks. I'll read that link later.

What is a hard fork?

I'm assuming that it's when a collective that are trusted within the Bitcoin community get together and shut the network down temporarily in order to install a modified version of the blockchain. I'm assuming this is to correct either an error or disadvantaged situation in the blockchain or to enable it to work with a change in Bitcoin protocol. Am I right?

I've also seen that there was a hard fork back in 2012. What happened and what was the reason for doing it?

Does a USB miner help to support the network, regardless of the money you may or may not earn from it?

Would hundreds of us using these be helping out transaction speeds and keeping the network distributed, or is it a drop in the ocean compared to serious mining rigs?

Oh, I didn't mean to come across as being unimpressed or scathing about waiting. I think the system is great: a truly sophisticated way of doing commerce. My opening post was done with good humour.

I want bitcoin to succeed and be everywhere, but in order for it to be used on every street corner I think it we will need quicker confirmations, else it may end up being used only for banking utilities and big purchases.

The last couple of BTC transactions I've done took about 10 mins to 1st confirmation. This was for small amounts (under $100) and I paid a 0.0002 transaction fee.

If we want bitcoin to take off with casual users is it likely that people are going to go into a shop and wait ten minutes to pay for a Mars bar and a pint of milk? If the shop requires three confirmations to sell then you could be looking at thirty minutes to get a packet of cigarettes and I can't see someone craving a fix of nicotine waiting for that long.

What's being done to enable transactions as quick as a credit/debit card?

If the global economy changed and if Bitcoin took its place would anything change? Would Bitcoin be largely owned by an elite, with the average person scrabbling about for less than a Satoshi?

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When the difficulty changes how is it set?

There can't be some kind of signal dispersed around the network, saying "difficulty change ... ...NOW!", can there?