the antec 900 is a good case, but some here would suggest the CM690 or the NZXT Tempest, so i would check those out also. but right now, newegg has the antec 900 for 60USD, free shipping. LOL
the HDD, some would suggest getting 2 seperate drivers, one for OS and such, and the other for multimedia, ect. because theres a possibility it might fail and atleast you wont lose all your data. but some who dont really care would like just one hard drive with everything on it. so its up to you, but im just throwing it out there.
everything else seems good to me.
oh yea, what resolution do plan on playing those games in?
secondly, i would suggest getting the q6600, q9300, or q9400. the q6600 is a great chip with a low price, while the q9300 and q9400 are slightly more expensive but are 45mm, which will help lower the temps on the chip. personally, i dont think you really need 2.83ghz quad-core, especially since your video card is a HD4850, so it seems likes bottle necking it. getting the q6600 will save you about $130.
for the hard drive, if your really on a budget, i guess 1TB HDD wouldnt be so bad. its not like its that bad, im just saying there is a small chance that it will fail anytime soon. it just depends how much space you need.
also, your missing a heatsink and fan for your cpu.
umm, the links you posted are like a list of products. but you can get the q6600, 2.4ghz, and OC it easily to 3.0ghz or even 3.5ghz if you cool it right.
for the video card, what resolution is your monitor? because if you have something less than 1650x1080, then the HD4850 should be suffice. if you have like a 24" monitor that supports 1080p, then i suggest the HD4870 1gb version. but i think this would go well over your $800 budget.
