i was looking for a USB mic to record vocals with overtop tracks with and came across two and wanted to ask the opinion of people who might know which one is better? Samson Q1UCW Handheld USB Microphone from zZounds.com Buy Nady USB-24M USB microphone online at Musician's Friend
this one, because it has a 24-bit/96KHz sampling rate whereas the first one is only 16-Bit/48kHz Sampling Rate which basically means you will be recording at a higher quality, however in some cases the quality of the input is not an issue, as most people can't distinguish between 16 & 24bit sound quality
I personally wouldn't recommend USB mics/speakers, because USB doesn't get high speeds (don't know if that is still the case today). It might be better to get a mic to connect to your sound card.