Hi, I'm gonna sell my old rig in a month or so... and just ordered some
RAM for my new rig. (It's this if you must know:
http://www.newegg.com/Product/Prod [...] 20145184). Okay,
obviously I ordered the new RAM to get the 40 clam mail in rebate. And
while I'm waiting to sell my old rig, could I use the new RAM in there?
I have this mobo:
http://www.newegg.com/product/prod [...] 6813128009
 
The unfortunate thing is that it only supports 4 gigs of RAM total, and
it has 4 RAM slots. Could I put 2x2GB sticks in there instead of my old
2x1GB + 2x512MB? Thanks.

Read the manual.