I'm gearing up to buy a 15" i7 MBP, and will probably upgrade it to 6GB RAM within the year, but can't decide whether to do so immediately. I'm liable to be running a few CS apps at once, and probably a VM or two (or three) at once for web browser testing purposes. Highest memory load would likely be Photoshop, Illustrator, Flash, and Dreamweaver all at once with no VMs, or 4 VMs (2 WinXP + 2 Win7) plus Photoshop and Dreamweaver. (In either case, I'd have mail, a few browser windows with a half-dozen tabs each, and probably iTunes running as well.) 4GB currently gives me just enough overhead for the 4 CS apps, but that's CS3, not CS5... and of course I can't virtualize Windows on the G5, so no idea how much memory that would likely need. How constricting will I find the 4GB to start off with?