[Shadowmeph]

it looks to me that you might have caught the bug .. the upgrade bug this is dangerous to have if you don't have the bucks hehe.
what type of editing are you doing I am not sure how much Cuda would make a difference on most editing because I think that it is a CL so it wouldn't really matter
personally I would just update the video card if you feel you have to. and if your system seems to stagger a little when you are encoding try to figure out what is causing it to stagger, you might just need to overclock a bit.