the amount of "bits" (16 bit, 24 bit) defines the number of voltage steps used in the sampling process. for example a 16-bit audio file uses just over 65,000 voltage steps to represent your sound, while a 24-bit file uses over 16,000,000! (so basically: more bits = a more accurate representation of the sound you originally recorded.)
the sample rate is the number of times per second that the voltage steps are recorded.
standard CD audio is 44.1kHz, 16-bit, while DVD audio is either 48kHz or 96kHz and 16- or 24-bit.
as for what you should use... well, there's nothing wrong with CD quality! (16-bit, 44.1kHz).
obviously if you plan to ever make surround-sound mixes of whatever it is you're recording, to be played on a DVD player, you'd be better off with 48kHz. but there's no reason why you can't re-sample your existing audio at 48kHz.
hope that was helpful..
-Mark