I wanted to upgrade my HD. I was wondering if I could take my older Hitachi SATA 160Gb HD, switch it w/ a new Seagate 320gb (SATA or ATA), and make my Hitachi a backup drive using an external enclosure setup. How would I go about doing that? How would I get Windows XP pro and all the other programs from the Hitachi to the Seagate? Is it a direct copy, or do I have to redo everything from scratch? Also, I would have to get a SATA enclosure, right? How do they work? Just a USB 2 connection like the ATA drive enclosures?
If this is too much of a hassle, the other option I was considering was to make the Seagate my backup drive and put it in the enclosure. Any help/thoughts would be much appreciated. Thanks.

AOpen AK86-L
AMD Athlon 64 3000
Radeon 9800 pro
Creative X-Fi Audio
1gb Corsair ram
Windows XP Pro
If this is too much of a hassle, the other option I was considering was to make the Seagate my backup drive and put it in the enclosure. Any help/thoughts would be much appreciated. Thanks.
AOpen AK86-L
AMD Athlon 64 3000
Radeon 9800 pro
Creative X-Fi Audio
1gb Corsair ram
Windows XP Pro