I've had 14 tracks with about 15 DX effect instances (reverb, compressor, and parametric EQ mostly) with n-Track 2.04 on NT4. No problems.
I don't know what my REAL limit is since I haven't hit it yet. According to dskbench I should be able to handle 30 tracks (assuming 64k block size) without any DX effects...so I'm probably getting close.
My system isn't the best either. Celeron 400 oc'ed to 500, 64MB, 5400RPM Quantum drive, cheap soundcard...etc.
Note that on Win98 my system started out fine, but before long 6-8 tracks became difficult. NT solved this problem...and made the crashes less bothersome (less crashing and virtually no rebooting).
It might also be interesting to know that I'm getting MUCH better performance using 3rd party FAT32 drivers for NT than I did using FAT16 on NT (I'm dual booting so FAT32 was my best option).
I'd say that Windows2000 will work out nicely. I'm using it now at work and haven't had any glitches thus far. Pray for more support.
Slackmaster 2000