Vid and ram question for a setup for 5 boxing, that i'm thinking of

Ok, I had some quickish questions. I'm thinking of springing for 2 newer computers, then manually upgrading vid cards on the (then) 3 to the 8800's. 5 box on 3 pc's. Now you can buy some decent pc's that can 2 box just fine, but I'd like to get the ram upgraded, also. I know on some of the older styles of ram, they pretty much had to be the same brand or very similar in performance. So with ddr2, can i just buy like 3 2g sticks and slap em in? The pc's I'd be looking for/at would already come with 2g ddr2, and then just add in a second stick and videocard, and keyclone em and go. It's looking like hardware is really preferable to keyclone, and I migt at some later date get a 4pt kvm and I think vetra multicaster, and ignore software emulation. Now that I say that out loud, as long as i dualbox, i'll have to keep keyclone. Maybe eventually a 4/5th computer then those other hardware solutions will come into play. With a 70's condo (built), I'll need to add a few more outlets. As it is, one pc currently is running off a heavy gauge extension cord, just so it can be near my main pc. And soonish, I'll have to add a third extension cord to bring a third pc to my desk.

Also you guys say 8800's are good but what ram? 256 could prolly work it fine, but I'll shoot for the 512mb models. I think the 768ram or w/e is nice but not paying 1500ish for 3 cards. And there may be cheaper models, but that was one place's price.