IDE is an internal connection, while USB is external.
If you want an internal drive you can choose between IDE/ATAPI or SCSI. SCSI is more expensive, you need a SCSI card as well, or on-board SCSI controller, but it is more stable and uses less CPU time. Although SCSI there are advantages to using SCSI, the extra money is hardly worth it if you do not have a SCSI adapter already.
Good value for money would be an IDE/ATAPI burner, preferably Plextor of course
If you want External you can choose between Parallel, USB, SCSI and FireWire/iLink. SCSI and iLink/FireWire (IEEE1394) require a special connection and are more expensive than Parallel and USB connections on a writer. Parallel and USB is present at all current PCs. Parallel is not recommended partially for its instability, but mostly for its speed and connectivity (device should be connected and turned on at reboot or else it won't work).
FreeCom has an external model which can be connected to different ports, depending on which cable you buy (sold seprately). For a review you can read this posting http://borg.cdfreaks.com/news2.php3?ID=1227.
But I asume you want an internal burner and therefor I will leave it at this. Buy Plextor