The OCZ stealthxtream 600w is a good PSU which can handle your system without any problem. It's not the best of the best, but it will do its work fine.
You can find some qualified reviews in the PSU Review Database (see my signature)
Concerning the graphic card, if it was my money I would go for the GTX460 1Gb model. It performs very well and the price is not too high. It's the best bang for the money nowadays.
NVIDIA offers two GTX 460 variants at launch time, one with 768 MB and one with 1 GB. Aside from the obvious potential confusion with end users, the differences in actual performance are rather slim. On average we see only 7% performance difference between both cards which is very small considering the 25% difference in specs for memory size, memory bus width and number of ROPs. Essentially this means that the 768 MB version is the one to get unless you have a specific reason you think you need more memory, or speculate on the higher resale value of the card at a later time. 9.5 out of 10 bestbuy award if the 1 gb is available and not more go for it otherwise the 768mb ain't a bad choice either
In saying that, we see some performance gains help us move past that 30 FPS minimum at the higher resolution which is important. The good news is that the 1GB version isn't all that much more expensive than the 768MB one. Also, compared to other models like the GTX 465 and HD 5830 to name just a few, the overall value is still better which is fantastic news for the consumer. http://www.tweaktown.com/reviews/3423/msi_geforce_gtx_4...
i play at 1920x1080.... and my budget its arround 500 i think, im not sure cause its like $800 in my country so...
For 1920x1080,definitely go with 1GB version,its worth it.
And for PSU,well a good alternative would be Corsair HX 620/HX 520,but if you can't get any of them,then the OCZ StealthXstream 600W that you chose will work
The sweet spot for PSU's is the 650 watters as they are often comparably proced to 50 and 600 watters. Since PSU's hit peak efficiency at 50% load, the extra headroom provides both a cushion and better eficiency.
For comparison purposes , the list below contains performance ratings (10 scale) at jonnyguru.com / prices as per newegg on 02/26/2010 and ones w/ double asterisk (**) made it onto silentpcreview.com's Editor's Choice List:
Note: Just because you see a brand name on this list, never make the assumption that their other lines are of matching quality. Silverstone for example has other models w/ 6.0 and 7.0 ratings.