If you plan on leaving it plugged in all the time and not moving data back and forth between laptop to desktop, desktop to desktop, or even laptop to laptop an eSata capable drive would be one thought since the drive would be under the onboard sata controllers and not the usb bus. Yet the 500gb WD usb model used here has been quite reliable once the factory Fat32 partition they come with saw a reformat to NTFS. No software needed for either XP or Vista to readily see the drive.
WD and Seagate both have some models to look through there. Both companies will also recommend seeing the factory partition replaced with NTFS for those using Windows alone and not running Apple/Mac. Still downloading a backup copy of the software for the drive you go with from the support is still a good move however for the initial reformat to NTFS or simply in the event you need to clean the drive for some other reason like a surprise virus.