Backup Storage Device

[Pickers]

Hey guys! I'm hoping someone can help me out here. I need a backup hard drive today, so will be going to PCWORLD, but dont really know whats a good price or whats good specs.
ideally 500Gb will do me. It would be nice if it didnt need its own power cable, but I think most do? Are the "portable" ones any good?
http://www.pcworld.co.uk/martprd/store/pcw_page.jsp?BV_SessionID=@@@@0723682074.125940998 8@@@@&BV_EngineID=ccfcadeimfdhhelcflgceggdhhmdgmj.0&category_oid=-32891&sku=655573&page=Product&fm=null&sm=null&tm=null
is one I've seen

edit: actually 320Gb would probably suffice!
http://www.pcworld.co.uk/martprd/store/pcw_page.jsp?BV_SessionID=@@@@0723682074.125940998 8@@@@&BV_EngineID=ccfcadeimfdhhelcflgceggdhhmdgmj.0&page=Product&sku=906252

[Davey_Pitch]

Seems like a decent price to me, and I love WD drives, I've got 4 of them (2 internal, 2 external) and so far they've been completely rock solid.

[Burble]

Portable drives tend to be USB powered so don't need an external power supply.

[Mark]

They also tend to be slower 5400RPM drives, but for a backup device that probably doesn't matter.

I'm heading to PC World shortly (mostly to browse) so I'll see if there are any in-store deals.

[Mark]

Out of stock of those drives in this PC World and the next cheapest (Seagate) is £10 more. Hope you find one.

Edit - aha. Found them. Big display I just walked past on the way in. :o