For starters, if you don't mind the idea of having a used video card (instead of 2 new 6770s - I see them listed for ~$110-120) you could try and get a 5970 which is still sort of within your $300 range.

The 5970 you can find used for ~$300-350 probably and it'll put out more mhash/sec and outperform crossfired 6770's for gaming. (Assuming the wiki is accurate; each 6770 = ~200 mhash/sec vs 5970 = ~650 mhash/sec; more if you overclock of course)

1) PSU: something around the 600-800W should do but would need to know what kind of CPU and GPU you decide on to give a more accurate number.  If you want to expand to 2 or 3 cards you might want a higher watt PSU as well but they can get expensive.

2 & 3) Motherboard/CPU:  I'll leave that to someone else to give you suggestions for well-priced to performance since I haven't been keeping up on them since the i7's came out.

As far as manufacturers go, should all be pretty much the same with a small amount of variance on how well you can overclock them (if you choose to do so).

Not my personal experience, but from reading, it would seem that some feel that:

-Sapphire's tend to overclock the best

-XFX has the best warranty (double lifetime warranty: meaning that you get the warranty, and if you/someone chooses to sell the card they can transfer the warranty).  Read a few comments on how the XFX's tend to go bad requiring the warranty to be as good as it is...

-Diamonds I haven't really heard anything good/bad about them so I guess they're solid performers?

Someone feel free to correct me.

Just sent 1.5 BTC to 1Hs3d5AiFRfzFsNohnHa2vv6Bo6RR7ztDX

On 2/7 1.8 BTC to be repaid to 1MLEfcwGN9txSTCf96WSLdAqZcwURriTsK

Check your PM kais3r.

Like iNs4nePT said, don't use nVidias.

Get a an ATI that's comparably priced to the GTX550s you're looking at and you'll get more mhash/sec for the money you put into the cards.  At $120 each, you could probably find some 5830's.  For a little more you could also get the 5850's or 5870's if you look around and find a good deal (on Craigslist/eBay and forums like this one or others).

GTX550's don't seem to be listed on the hardware comparison wiki (https://en.bitcoin.it/wiki/Mining_hardware_comparison), but someone in another thread mentioned that he was getting about 30-40 mhash/sec (https://bitcointalk.org/index.php?topic=61292.msg715196#msg715196).

For the same price, the 5830's are supposed to put out around 286.45 mhash/sec.

As for the other stuff and whether or not OS makes a difference, I have no clue myself.

Edit: Guy above beat me to it.  Although from my short time here, it seems like the 5800 series are some of the go-to cards for mhash/$ value?  It's hard to find brand new ones though if you're worried about them dying on you before you get enough mining time out of 'em.

Beats me, but I would think their ability to retain value would be pegged according to the value/difficulty of bitcoins since they'd have little to no use for people besides mining?

With Radeon GPUs, you can sell it to someone for mining or to someone who intends to use it for gaming making it easier to sell and hold value.

The problem is that you're trying to get people to do something that requires a great amount trust to do when you have yet to earn any trust.  And even the ones with trust wouldn't be likely to get someone to just lend them stuff for the hell of it.  They'd just go and read up a bunch on others' experiences with FPGA's.

That, and you're not trying to spend any money to make a large sum of money; you're just hoping someone will loan you something that's worth $500+ for an extended period of time (when they could be using their hardware to mine for bitcoins for themselves).

Yup, and to further iterate.

Look in the top-left corner of the forum page.

It'll say "Hello <your name"; and then under it it'll say "Total time logged in:".

Once it reaches 4 hours you're good to go.

LOL, this.

Don't ever put personal information up on the Internet.

Chances are it's just some prick troll that thought it'd be funny.

You could always try to do a reverse phone look up or register his phone number to a shetload of junkmail/spam sites for being a jack@ss.

I hope so.  I've got my resume up on Monster, my university job board, and sent some to friends/classmates and hopefully something will pan out.  Gotta get started on paying off my student loans soon.

Got a couple calls from Monster but the jobs weren't exactly what I'm looking for.  One was for demo'ing a company's software to customers that their sales team locates.  So I'd just be learning about their product instead of a skillset that I can bring with me to another place.

The other was just from a headhunter company that wants to hole me up in helpdesk and they wanna give me $12/hr for 6 months with no benefits (they said I'd be getting public trust but yeah... if they put in writing that they'd put me in for a security clearance I'd suck it up and take it).

CCIE, nice.  I just got my CCNA but that's just all book learning and simulator with no enterprise environment experience.

I'm in the DC area so hopefully I can land something with one of the big defense contractors.

Got a couple years of IT experience, just finished my Bachelor's.  Got some certifications as well and currently trying to get back into the job market.

I see, thanks for the quick responses.

Guess I'll see if I can get my hand on one or two to use and then try to sell them to put towards the 7990s.

And, like you said, if the prices drop too much I'll just run them 'til they die.

Do you guys think the 5970's will hold their resale value fairly well once the 7990s are out?

Wondering if it might be a fairly safe idea to buy a 5970 for ~$300-350ish, mine until the 7990s are released, then try to sell the 5970 for about how much I paid for it to put towards a 7990.

Any thoughts are appreciated.  I'm sure there are some people here who have been around long enough to have seen how the release of next gen video cards have affected the older gens' values.

Yup, sig thing won't be much good either like copumpkin mentioned.

Would be a pain, but maybe you should reformat your computer, install an anti-virus on it right away, then sign in and change your password and stuff up.

Well, if they're relatives I don't see why they can't just send you money through PayPal (have them denote it as being a gift).  Being relatives I would hope you wouldn't have to worry about them scamming you or something and doing a chargeback lol

If they fund the send request with a bank account there's no fee; if they fund it with a credit card there's a fee (they choose to have either you or them pay the fee).

And then you send them the bitcoins and it's done.

FreeMoney is a good guy.  Was quick with communication and sent the bitcoins as promised after I forwarded him the purchase receipt.

PM'd him and bought.  Good with communications and he sent me the Mt.Gox code first.

It's $0.11 per kWh here in VA.

Bought one of those kill a watt things to see how much power my PC draws but I still don't have any good mining GPUs to calculate with yet... I've been an nVidia guy but hoping to find some 5870's at some point.

Unfortunately I got some old GTX 260's too (~45 mhash/sec)...

Should sell mine and look for 5870's but it seems like all the decently well priced ones sold by people are bought up so quickly...

Hoping to maybe talk a couple people on Craigslist in my area down on the prices (they want $180 and $200 respectively).

Lol works for me, wish they gave more slowly but beggars can't be choosers.