Tyan Tiger K7 (because I want to use my QuietPC 300W supply)
4x 1 GB DDR
Fujitsu 40GB (again, for the low noise reason, SilentDrive, etc.)
Install Windows 2000 on a 2 GB RAM Disk.

Install software on it also.
In the worst case, I can install Windows on the hard drive and load everything on the RAM Disk.
I ran a test on my Athlon with Outlook search. I had a 50MB .pst file and the difference of performance was unbelievable.

Such upgrade will surely keep me away from upgrading for about one or two years.

(or not..)