I just got the T7600 chip and 441695-001 motherboard. Say what you like about Vista, but I put in them both in with the 4GB RAM and it booted first time. I was quite impressed. Once in Windows it did ask me to reboot once to update the CPU drivers, but that was all. I got the motherboard for 10 quid on ebay. It was sold as assumed faulty but really it was just untested.
My Windows experience index went from 3.6, 4.5, 2.5, 2.8, 4.3 to 5.2, 4.7, 3.5, 3.1, 4.3. Previously I had 2GB of RAM, the 445605-001 motherboard (presumed - it had no label) and the 1.73 GHz celeron chip.
I can now play 1080p video, before it would max out the CPU and freeze up.
I still am waiting on the SSD, I will see if that gives more improvement.
Thanks for all the help Shadow Fox and C500 fan, I couldn't have done it without all your invaluable information in this thread!