I'm using both an external AC powered drive (Maxtor), and a USB powered pocket drive (Freecom). I use the Maxtor drive to store my entire music collection in Windows Media Lossless format, together with multiple full uncompressed backups of my main desktop machine. The pocket drive, is used to store the same music collection in various levels of MP format.
The Maxtor drive has dual connection options, in Firewire and USB 2.0 It also has a neat bit of bundled software for backing up, using a dedicated button on the drive. This drive works flawlessly, with my Windows XP system, running on an ancient AMD Duron 1.2 processor, with 512MB RAM.
The pocket drive is quite new (about 2 weeks), but so far is proving to be a great piece of kit. The fact that it it's so slim (fits in the palm of your hand), and USB powered, means it's so easy to slip in the laptop bag.
Incidently, there are Wireless network drive enclosures/adapters appearing on the market now, meaning with the right setup I can use the Maxtor drive without it needing to be connected to any particular pc.
