I've found that if you stop all the HP related software running at startup it stops things slowing down.
Goto Start / Run, type msconfig in the box, then click the startup tab, remove the ticks from everything HP related, then restart your PC, this won't effect your printer in any way, although you may find print jobs take slightly longer to start.
Norton AV will slow your PC down as it's scanning every file on your disk & comparing them to a database, this is pretty processor intensive and it slows down disk access.
As for the Fellows labelling kit, it's probably very badly written, so don't run it while you're writing CDs to prevent ruined disks.
Hope this helps