Derik at MacUser has a very nicely written piece about the ability of MacBooks to handle 3GB or RAM. Apparently the Core 2 Duo based MacBooks (not to be confused with the first gen Core Duo MacBooks) are able to max out at 3 gigs of Memory. But Apple’s not keen on advertising that, as it means using mismatched pairs of Memory, which can cause a loss of system speed with the Graphics Card being tied to the same memory. Probably not worth that kind of hit, but if you absolutely must have the power, I suppose this is the way to go.
If you’ve got this setup, I’d be interested to hear your thoughts on speed trade-offs.