Have you ever tried to do a CD copy from a source drive (CD, DVD, CDRW, ...) on the same IDE controller than the one used by ur burner ?
Don't bet on it even w/ a fast CPU and a speedy HD without using the BurnProof technology.
I do that nowadays w/ my Plextor PX-W1210A while surfing, DLing, or even playing. It never failed even if Nero complaints about it before starting the burning process.
So IMHO spending an extra $250 can definitely be worthwhile