CDwave = good
Audacity = good
Vegas = Don't know
I've used XP, Vista, MAC OSX, and WIN 7...and WIN 7 is the best out of all of them (just as long as you're not an idiot and click links in emails or surf a lot of Porn).
Especially when you factor in the cost of the hardware, Win 7 beats OSX hands down. For lazy morons, OSX is the way to go. You don't have to worry about viruses, but Microsoft now offers free quality anti-virus software, so dollar for dollar I think Win 7 wins.
Sound Forge also works on Win 7. I've gotten Wavelab to work, but it's not 100% reliable.