New to the mining community, need direction.

[b3st0fth3w0rst]

Hello everyone. Ive decided to delve into the world of bitcoin/litecoin mining but there are a few things that i'm still unclear about.
I mainly want to do this as a project and i'm familiar with building my own PCs etc, but also making a profitable return would be nice.

Currently i am mining at hascows with a xfx 6850 @ 275 KHash/s with cgminer OC 975MHz 1020 mem OC @ 45C temps.

I plan on buying new hardware, either to mine bitcoins or mine litecoins, but i'm a little weary. According to this calculator: http://www.bitcoinx.com/profit/ with the following parameters...

Bitcoin difficulty - 2,621,404,453   
Bitcoins per Block (BTC/block) - 25.00
Conversion rate (USD/BTC) - 782.38
Hash rate - 1TH/s
Electricity rate (USD/kWh) - 0.11kWh
Power consumption (W) - 1000
Time frame (months) - 1
Cost of mining hardware (USD) - 0
Profitability decline per year - 0.61

I stand to make per month:
Power cost per 24h - 2.64 USD
Revenue per day   - 150.10 USD
Less power costs   - 147.46 USD
System efficiency    - 1000.00 MH/s/W
Power cost per time frame - 80.36 USD
Revenue per time frame - 4475.82 USD
Less power costs   - 4395.47 USD

Are these calculators accurate to some degree? meaning, if i were to fork over the cash right now to wither build or buy a 1TH/s ASIC miner, i could expect returns like the above? For some reason i feel like i'm missing something, because it seems like it would be too easy.

Thank you in advance. As i am new to this scene, any and all comments/help/advice would be much appreciated.
If i'm going to be spending money in build my own miner, i'd just like a push in the right direction on what i can expect as far as returns (meaning can i trust these online calculators), issues i may encounter, maybe hardware that i should avoid.

Again...thanks for your help.

[vpasic]

first of all you forgot to enter cost of mining hardware.
second thing there is no 1TH mining hardware for you to buy RIGHT NOW to start mining.
sure, you can order like 5 antminers but that will take a months to ROI if ever!
even if you order 2TH from black arrow or 3TH from knc you will have it in your hands to late to even make positive ROI and specially not earning like $4400/month.
also forget about gpu rigs since scrypt asic-s are around the corner and it is matter of months wen gpu-s will be run over by asic.
this is really not the time to make any investments in mining gear.
my suggestion is to wait till summer for next generation of miners (5-7TH) and be fast on buying.
keep an eye on kncminer and black arrow.

mining.thegenesisblock.com is much realistic calculator.

[b3st0fth3w0rst]

first of all you forgot to enter cost of mining hardware.
second thing there is no 1TH mining hardware for you to buy RIGHT NOW to start mining.
sure, you can order like 5 antminers but that will take a months to ROI if ever!
even if you order 2TH from black arrow or 3TH from knc you will have it in your hands to late to even make positive ROI and specially not earning like $4400/month.
also forget about gpu rigs since scrypt asic-s are around the corner and it is matter of months wen gpu-s will be run over by asic.
this is really not the time to make any investments in mining gear.
my suggestion is to wait till summer for next generation of miners (5-7TH) and be fast on buying.
keep an eye on kncminer and black arrow.

mining.thegenesisblock.com is much realistic calculator.

Thanks for your response. i just plugged in 1TH/s mining machine as an example. But in any event i was more looking to find out if the outcome from the online bitcoin/litecoin calculators where accurate to some extent. So if i plug in some numbers and then go about building said machine, i can reliably expect the return to be somewhere close to what the calculator says (of course i dont expect the exact amount and there are a number of other variables that could affect return).

I have read that scrypt asics are just around the corner as well, so that kinda puts a damper on the gpu mining plans. I was thinking of building a scrypt miner with 3-4 290x gpus or 1-2 7990s if i could find them, but with asic for scrypt around the corner, as you suggest, it might not be such a good time to do so.