XP 32, XP 64, Vista 32, or Vista 64?
I prefer Vista 64-bit. XP 64-bit is not an option for you with boot camp. There are no drivers available for the Macbook Pro for XP 64-bit (and no, they can't use XP 32-bit drivers, you need 64-bit drivers). Vista's memory management is very much like that of Mac OS X's. XP's memory management sucks. Its memory management is catered to older computers, since it was designed with those computers in mind (think about it, it was released in 2001). Yes, SPs were released, but none of them changed XP's kernel. It's basically a bunch of patches/updates/ect rolled into one with a few other things thrown in.
Anyway. Vista's memory management will use your free memory to cache programs. When a program needs the memory, Vista releases it. It's called super fetch. Leopard does the same thing. Vista's actually got a search function built in that's worth a crap, although there is a Windows Search 4.0 update for XP, but it's just "tacked on." It doesn't integrate into explorer. It's similar to google's desktop search. If you have 4 gigs of RAM (which you do), Vista will run fine on it. SP1 fixed many of Vista's problems and hardware manufacturers have drivers out for Vista that don't suck. Vista's been out for a year and a half, and it's approaching 2 years since it's been completed.
- Can XP support over 2GB of ram?
Yes. It supports 4 gigs of system memory, or address space. All 32-bit operating systems do. However, video card memory uses this address space, input/output port space uses this address space, virtual memory (although I believe they now have it so that virtual memory is mapped outside the main address space), and there are many more.
the big ones though is video card memory and "everything else."
Because of this, whatever is left over after the video card's taken a chunk out of the address space, and "everything else," will determine how much RAM is available.
So basically, under 4 gigs of RAM will be available. Between 3 and 3.5 gigs will be available to you with a 32-bit OS. Vista 64-bit will solve this (as it has a much larger address space, 2^64 to be exact).
- is vista a lot less efficient than XP
I personally feel that XP is less efficient than Vista. Nowadays, any OS that just lets your RAM sit idle and do NOTHING is not efficient. It's a waste. Unused RAM is wasted RAM. Vista also moves desktop rendering to the video card (it used to be done by the CPU under XP), like what Mac OS X uses.
- is my graphics card even dx10? if so does that make vista a must?
Yes, it is DX10. No, you don't need Vista. If you play a game that is DX10 and supports DX9, you will play it under DX9. DX10 "features," might be able to be enabled depending on the game.
- whats the deal with the driver issues I'm hearing about with XP(seen a lot of different opinions on this)
Don't know. I think it was mainly people with the new MBPs.