Help for upgrading

Guys I was wondering should I buy GTX 285 (1 GB) or a 4870 X2 (2 GB)? Specs in sign.

P.S. I have 600 W PSU, so do I have to change it for 4870? If yes, then which is the best one right now to get it? I am going to buy it from Newegg.ca Thanks.

from your rig spec i say you should change your PSU,regardless any VGA you choose. i recommend HD4870 X2, a Corsair TX 750W and a Windows 7 64bit (cos Vista 64bit sucks) :)AMDAtiFanboy

I was thinking of getting this PSU. So, do I have to change the case as well or should I get this one you said, i.e. Corsair TX 750W?

Windows 7? You mean I have to wait till 2010? Or should I get the beta?

Hmmm... Looks like the combo of PSU+Video card seems to be expensive for my pocket. So, I was thinking of getting this card instead. Nvidia website says this card needs minimum of 550W PSU. So, is it possible for me to run on my current 600W? I have checked the dimensions of the card and it will easily fit in my case as it is exactly the same as my current card (it's big, btw).

Now, should I get this one or this one? If I get this ATI card as I mentioned earlier, then I have change the PSU as well! :( So, what should be the best thing to go for? Or should I wait a month or two to get the prices go down?

P.S. I was wondering where in Canada I can sell my stuff (other than ebay) cause I wanna get rid of some cards and my current monitor (and get a 22" Samsung). I got this website, but you guys have any other ideas?