I just took a look at my previous answer :) Brace yourself for this!!! Early iMacs came with USB connections only (for external gizmos like Zip drives etc..) and it was USB 1.0 which was really quite slow. The only benefits were that it was compatible with Macs and PCs and was 'hot pluggable' - i.e you could plug/unplug it with the computer still running. Firewire was Apple's improvement on USB, as it was a lot faster, in fact as fast as SCSI (an even earlier type of connection which had the downside of you having to switch your machine off to plug things in). So in a nutshell, if you have one of the early iMacs with a tray-loading CD then you only have USB connections. The later ones came with FireWire AND USB connections. Try MacWarehouse.co.uk and ask them if they have an external USB CD-burner. Give them your machine details, r.e. operating system etc and you should get something suitable. If you get stuck just post on here again though.. I'm always hovering :)