Slow computer with iPod

I recently purchased a new 15 gig iPod. I have the iTunes software installed for it as well. Whenever I plug in the iPod to update it while playing music the music starts to stop and become very spotty in its playback to the point where it’s unlistenable. This has been happening lately with any music I play whenever I’m running more than one program at once as well. My computer is roughly a year old. I have 2ghz, 40 Gig HDD, and 512 mb of RAM, so it should (and used to) be able to handle this easily. I’ve gone through and corrected the registry of errors, disabled any unnecessary start up items as well, run Norton Anti-Virus, and done a defrag. So what gives? Any help is appreciated.

CMiller