If you add an external CD burner to your Mac, I think you'd want one that uses the firewire protocol rather than USB. Firewire is native to Macs.
Also, you should get better results copying the CD to the hard drive rather than duping straight from a CD reader to the CD burner.
Also, you should get better results copying the CD to the hard drive rather than duping straight from a CD reader to the CD burner.