I'm gonna split this a little...
If you need audio only, i'd recommend Steinberg's Wavelab, Sonic Foundy's Soundforge or Sek'd's Samplitude - those are professional and are priced accordingly...
Syntrilium's Cool Edit Pro is also good with a great price...
For audio/midi my favorite is Steinberg's Cubase 5 or the new Nuendo, especially with VST effects and instruments (Prophet 5 and Hammond B4 can be had) - there's a light version of Cubase called Cubasis...A lot of Mac users swear by Emagic's Logic Audio, but its PC versions tend to be buggy...
Those programs usually are in the 300 to 600$ price range...
http://harmony-central.com and
http://www.cubase.net are good places for getting information on this subject...