I've used Cakewalk Pro 3 since 1995 (!!!). I used to have that on a 75 MHz PC, also running Turtle Beach Tropez sound card for all my .WAV sampling needs.
It was such a stable system (I still have that old PC baseunit in a box
Cakewalk 3 was probably the last great MIDI only sequencer and has run fine on all Windows versions from 3.11, 95, 98, 2000, XP and Vista ! (I haven't tried Windows 7 yet). My only grip is the .WRK filenames can only be 8 characters long (That's old DOS rules for you !). I use it on a Sony VAIO now. I might move that to a netbook and see if that also works.
You'll probably label me a dinosaur by not venturing into PC Virtual Synths & Effects, but Cakewalk has everything I've ever needed, especially as most of my gear is over 15 years old. My samples are now in an AKAI S6000 and editing is done using Goldwave (the best sound editor around - and it's totally free !

Kind Regards, Simon.
Instruments : Roland (SH-101, D550, M-VS1, AX7), Korg (EX-8000, DS-8, M1R, MS2000, KR55 & 55B), Ensoniq Mirage, Novation Super Bass Station, Electrix Warp Factory, Univox SR95, Electro Harmonix Small Stone x2