[nocat]

I agree with RB, although you can plug your instrument directly to the Line In on your
sound card, it's always a good idea to be able to control the signal before it gets there.
A cheap mixer is probably the most economical way to do this. Not only does it give you
the ability to control parameters like Trim, High and Low EQ, Pan and Fade, but also
makes it easy to switch instruments...!!!
As far as the bass. Using a condenser mic to record the sound from your bass amp will
probably yield poor results... Like RB said, record your bass directly into your PC, keeping
the sound as clean as possible, and then EQ it and compress it in Audacity to achieve
the sound you want...!!!

Cheers
Ben