Huh? I don't follow you Bobcat1132...
You can mix 'n' match pc2100, 2700, 3200 and 4000, the only "problem" is that they will only run as fast as the slowest chip.
But that doesn't mean you should buy the same speed that you currently have. Buy one chip of PC3200 now and combine it with your current PC2100. When you have saved up some more cash, and the price has come down a bit more, buy a second chip of PC3200 and dump the PC2100.
If you buy PC2100 now, you'll have to buy all new chips when you upgrade later.
And as for the graphics chip, you mostly use shared memory when you're using onboard graphics... And since he has just ordered a new card, he won't have to worry much about the video card eating up his system memory, unless he has bought a 64mb ram card and even then chances are that it won't use any of the system memory, but run slow as.......