I have 2 hard drives, both as masters on a Promise Ultra 66 card, HP 8100 burner as master on IDE channel 1, Kenwood 72X as primary on IDE channel 2.
If burning from hard drive I put the file on my D drive (all o/s and proggies are on C drive. So regardless whether I'm buring from hard drive or cd to cd, I can surf and generally do whatever I want without worrying about coasters.