Brando Workshop has released a USB Portable DVD Multi Drive for only $78, which looks like a great price.
If lack of a DVD Drive is the drawback of your PC/notebook, like the new Asus Eee PC and Macbook Air, you may consider this USB Portable DVD Multi Drive. It is compatible with all computers and notebook, as long as they have a USB port.
Drive: Matshita DVD-RAM UJ-841S
CD Read/Write speed: 24x, 10x
DVD Read/Write speed: 8x, 4x, 2.4x, 5x
Support Media(Read): DVD+R, DVD+RW, DVD-R, DVD-RW, DVD-RAM, DVD-ROM, DVD-R DL, DVD+R DL, CD-R, CD-RW, CD-ROM, DVD-R DL, DVD+R DL
Support Media(Write): DVD+R, DVD+RW, DVD-R, DVD-RW, DVD-RAM DVD-R DL, DVD+R DL, CD-R, CD-RW, DVD-R DL, DVD+R DL
Modes: Packet, TAO, DAO, SAO, RAW SAO
Buffer Memory: 2MB
Size: 13.7 x 13.3 x 1.8 cm
Operating System: Windows Vista, Windows XP Home or Professional (SP2), Windows 2000 (SP4)