Hi,
To quickly asnwer your questions,
1. Buy AMD dualcore Opterons instead, you're better off. Check the
threads on this from a couple of days ago.
Also some links:
http://www.digit-life.com/articles2/cpu/amd-cmp-vs-smp.html
And
http://www.gamepc.com/labs/view_content.asp?id=a64x2&page=1&MSCSProfile=
95385A1F52DEA1A229D5B3754205446469A9660B0657543D6291E8AC89831F643531AE34
81763812CF6658D8B4DF5C424B99BB40E71F65CB454793C3AE37AE860F8F0127A58C6319
1D15DAF8193E518376033E41EA0A167B3C71E4919A00E266E30B5D0745D682F69AEAD359
004501E20E8460358E97F324D7FE53D6FA88DD7C3D4633430130BF5C
2. About WINXP64 you've hit the nail right on, it's all about
driversupport. But now with all the new applications moving over to 64
bit, WINXP64 is gaining more support and driversupport etc. will
improve. Also when XSI 64 is available a lot of the more popular
plugins/addons hopefully will be recompiled quickly to the new platform.