320 - 500 GB Portable hard drive

Looking for a cheap Portable hard drive that I will be able to use with my laptop at home and also take to college to store my work on.

im looking to spend under £50 as I have seen a couple for around the £44 mark. It would need to have USB connection for when I use it in college, but I do believe my laptop has an E-SATA port (might be wrong?) so if there is one with both USB and E-SATA then that would also do. Cheers for any deals you find! :)