Building a Budget PC Need help on Graphics Options

Well i was fist looking at a 7870. im going to be playing valve games(CS GO, tf2, black messa), mc, lol, possibly Diablo, BF3, and crysis 3. is the 7870 overkill? i have 900p res. monitor and i dont plan on upgrading it soon. 

>900p wut

and yes possibly overkill but for the price you won't get much better considering it's only ~$50 more than a 7850 and you wouldn't want to go lower than that.

my res is 1600x 900. 

Please tell us what country you reside in, we can then look at sites in your part of the globe, also.... what budget?

The HD 7850 would be ideal if you are on a budget. I'd get it.