It's dual-core, 3ghz per core. Here is the CPU specs:
http://products.amd.com/en-us/Deskto...il.aspx?id=149

Motherboard is an ASUS M2R32-MVP, I use the stock heatsink that came with the retail version of the CPU. It's fairly quiet and 100% stable.

I do somewhat regret not going with a quad-core Intel machine but this cost probably 1/2 or 1/3 of what I'd have spent on a quad core box.

w.r.t. the 4GB memory limit in XP 32-bit, yep even with various boot.ini switches you'll never see more than ~3.5GB or so. I've heard that some motherboards have some BIOS trickery to get around this, but it appears mine does not. I do have a copy of XP 64-bit, and a copy of Vista... both of which would fix the problem. In the next week or so I'm going to try them out - separate installs onto spare HDDs - to work out any driver problems and compare the performance.