No idea... I've never used Windows and don't know anything about it sorry.
Personally, my next step would (still) be getting a cache to work. One thing at a time. In my experience, that's the most critical factor for Moodle performance.
I've never found ramdisks to be anything special in 'real life' applications - but I've not had the time or inclination to investigate further than that.
Just my $00.02, as they say.