Exactly, I would capitalize while the prices are low, you may not need it now, but down the road, it could save you from upgrading.
look at the CPU charts at tomshardware. I can guarantee the Core 2's will out perform the AMD's and are right around the same price.
I do a lot of computer work building systems, including laptops, so believe me when I say you will have a lot less driver problems and such going with the Intel platform.
Windows XP will only see slightly over 3 gigs of ram, you wont get all 4, Vista will support 4+ gigs however.