Some of you are looking at a PSU from a wattage perspective. You should be looking at the PSU from a amperage perspective as well. I am not sure of the name of his Antec 650 but he needs to know the amperage of the 12V rail along with the wattage in this case. Also, many are using 4850 to crossfire their cards with XP with no problems. Therefore, XP does not cause this type of problem, it's something else. Cat 8.8 should be out any day now and believe that should help the situation. From reading the OP's post(s) I haven't found any information that pinpoints what problems he is having. Yes, he says:
lag problems
still having same problems
etqw
But all he is saying is that he has a problem, nothing specific. What type of problem is the OP having? Has he tried to use a single card to see if the problem is gone? etc... If you look at
this review, it's clear that ET:QW has a history of not scaling properly using CF. Therefore, it's true that there has been problems with QW: ET.
Suggestion:
I am going to take a wild guess that his problem maybe related to poor CF performance in a single game QW: ET and nothing else. As he has never mention a series of games in his follow up posts (as his title seems to imply). Change the .exe of QW:ET to either:
AFR-FriendlyD3D.exe (This should allow AFR to work when CF is used)
or
WarGame-G4WLive.exe (This is specific profile command for UT3 engine)
See which works better for you.
Side note:
Maybe in the future the OP should try to properly title his thread so it's clear how we can help?