I bought a adapter or converter which can convert an IDE hard disk or SATA disk to a USB external drive.

1. Connect laptop 2.5" harddisk (IDE/SATA) to any computer via USB without power adaptor
2. Connect desktop 3.5" harddisk (IDE/SATA) to any computer via USB with power adaptor
3. Connect CD-ROM/CD-RW/DVD-ROM/DVD-RW (IDE/SATA) to any computer with power adaptor.
I tested it with my 3.5" 40GB Maxtor hard disk. It works on my Windows XP and O!play media player.
It is $20 plus tax.
nice one, a get $5 today