I use Windows XP x64 on a somewhat similar system. Windows XP Pro would only see 3GB of RAM on my system. As of right now, I have drivers for everything, including my Gretag Macbeth color management system, but be careful to check compatibility before making the switch. Being able to use the extra RAM in Photoshop (it supports up to somewhere around 2.7GB when run under x64) and still having extra left over for other applications is a wonderful thing if you're a photographer with a high-res DSLR. Depending on the kinds of things that you write programs to do, the extra RAM may be of use to you as well, but either way, it seems that x64 is a bit "snappier" than XP in general multitasking (speculated to be due to the access to additional general purpose registers on the CPU, among other things).
Photoshop is still a 32 bit app, you know. Besides, /3GB is not an option for some of us, who experience all sorts of weird side effects from enabling it (in my case, it made my graphics adapter behave like it was running on generic VESA drivers in 16 bit color). The other advantage of having 2.7GB (over 2GB) and 4GB total (over 3GB) is that plugins can access extra RAM above that, and Window can cache PS scratch file operations in RAM. Overall, Windows XP x64 does indeed give advantages for PS work over XP32 (even with the often ill-behaved /3GB switch).
Yeah, however my NVidia Geforce 6600 (how much more standard or reliable could you get in terms of drivers, other than Intel integrated [puke] graphics?) works just fine otherwise, and given that as a student, my license covers 32 bit or 64 bit XP (whichever I choose), I'd rather take the option that 1)works with all my hardware, 2)isn't an ugly hack, 3) doesn't require wasting lots of money and time to search for something that isn't well documented and just might work right, and 3) allows me to utilize all of my RAM.
