I now have SimCity 3000 working on xp pro sp2. I am running an AMD64 3000 processor, 1gb dual mem, twin gf6600 sli graphics cards.
The game runs in 32bit colour depth and at 1280 x 1024 resolution. It looks lovely! I havn't needed to change any compatibility settings.
I tried to install in on my AMD64, the installation would start, but when it reached the blue screen it wouldn't go any further, no error message, just stop.
I ended up installing it without a hitch on an old Dell Latitude 400mhz laptop i got, running xp pro sp2. I then installed the BAT patch:
http://simcity3000unlimited.ea.com/us/simexchange/downloads/sc3k_bat/index.phtml
It ran without any problems on the laptop. I then, over the LAN, copied the whole C:\program files\Maxis directory to the AMD64.
I run the game from C:\program files\maxis\simcity 3000\game\sc3.exe
I get 2 error messages when the game loads, and after that it's fine.