AOA member ThunderRd has just put up a Guide to Quad Core folding for windows.

Posted by ThunderRd:

This is a companion to ccperf's Dual Linux SMP clients how-to, for the LINUX-impaired.
I have, as a test, replaced one of my 925 dual cores with a Q6600 a few days ago. Just a straight drop-in, no muss/no fuss, no overclocking as yet. It's in one of my home machines, folding 24/7 on XP.

With no special attention it ran 10-11 minute step times on the SMP client. That's about 2100 PPD out of the box.

But here's the good news: are you aware that you can run 2 SMP clients on your quads? Now, there are several ways to do this. You can simply install another instance of the client and run it, XP setting both clients to use all cores. This works, but it isn't the fastest way. The next way is to manually set the affinity of the first client to 2 cores, and the second client to the other two. This is faster, but it's difficult to know how Windows detected the cores on boot and which two cores currently share cache. There are various combinations that windows uses, and it can change on rebooting so it's not always the same. Also, you'd have to babysit the clients and manually set the affinity each time a new WU is started; windows has no ability to pass the affinity assignment from parent to child processes in the FAH setup. So this isn't the most efficient way to run 2 clients, either.

Read the Guide Here