Hi Ben, alright mate.
well I've only got 60gb on the laptop. I've got quite a bit of music and getting more into photography so need a lot more space for photos and want to dump everything off of the laptop onto a faster hard drive and just keep stuff I use regularly on the laptop.
Plus if my laptop was stolen I'd lose all my college work and memorable pics etc.
300+ should be plenty, the same version of HD with 320gb on ebuyer is £59.41 so the 400gb looked like the one to go for.