I'm now successfully running WinXP Home Edition as DomU under XEN, with Gentoo Linux dom0. Xen and Linux kernel souce code installed from Gentoo emerge sources (not from the xensource tarball).
Hardware: HP Pavilion model d4600y, Core2 Duo CPU, Intel P965 chip set. (Despite predictions elsewhere on this mailing list, the P965 _does_ seem to work just fine for VT.
The BIOS does NOT ask whether you want to enable/disable VT, but I presume it must just always enable it, since it works.
If anybody else is having trouble getting VT working on this system/cpu/chipset combo, I'll be glad to compare notes. But there really was no trick to it. I just went back over all the instructions and re-did everything with more careful attention to detail. The Xen Technical Note V07134006 "How to Install Windows on Xen
3.0" is a must-read.
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