I, too, have a Western Digital 'Passport', the 250Gb one. I've been using it mobile for over a year, now, and it still behaves impeccably.

I do occasionally have trouble with it on some PCs because it needs more current from the USB than they are prepared to give, but WD Support sent me a dual USB lead which solved the problem. Beats me why they don't include it as standard... it can't really be that big a cost saving, surely?!

The most common problem with external drives seems to be running too hot, but I've got a couple of Toshiba 1Tb units (Stor E alu) that are always cool to the touch. I don't carry them around, though - one is on my desk at work, and the other at home. Not the fastest external drives I've seen, but reliable (so far!). They have the brightest blue LED I've ever seen fitted to such equipment!

If you're buying an external caddy to put a drive in, make sure the heat dissipation is good. One with a plastic case won't do as well as one with an aluminium case.

I have some Netgear SC101 Network Attached Storage devices in my home studio. Each can take two IDE drives either in 'mirrored' configuration, or the total capacity of both drives.

One of them failed a while ago (under warranty), although the drives survived. Interestingly, the replacement has been redesigned to incorporate a couple of small thermostatically controlled fans.