music software issues

[DiaKMS]

I was wondering if anyone could help me with a problem I've been having - whenever I try and record my vocals on top of an instrumental, the vocals somehow end up slightly un-synchronised with the rest of the track... and it's not just my lousy sense of rhythm, honest ;) anyways, this problem only occurs with my new microphone, which is called MXL USB 006, and is a sort of plug-and-play thingy. The software I use is called Cakewalk Guitar Tracks - tried looking on the website, and it says to 'set the playback timing master'. Only problem is, there's no 'playback timing master' on my edition of Cakewalk. The website also says that there might be a problem with synchronisation if the computer has more than one soundcard, but I only have the one - SoundMAX Digital Audio (dunno whether it's a rubbish one & therefore the cause of the problem??). ... wow that was long. Anyways, anyone who helps out gets a mention on my music myspace ;) Thank you in advance!

[itbloke]

I'm not sure but it might be sampling rate - can you check if your music track has the same sampling rate as the vocal track you are trying to overlay?

It may be also data x-fer rates due to using a USB mic. Have you tried an analogue one connected into your sound card?