If you are going to go the PC rout Id have a very long look at Sonar.
I used it for 2 years and thought it was great.

Also consider must have plugins like Antaries Autotune and Waves Gold. Not cheap but very nice.

Another really good idea for Bass and Vocals is getting a pre amp / channel strip than can interface with your sound card digitally (vis S/PDIF or something). Behringer (ultravoice pro) and ART make reasonably cheap ones and they will infinitely improve the way even an SM57 or an SM58 sounds.