Replying to I need a new external HD what one should i get?

ok, so i have a 320gig external HD and theres only 1.8 gigs left on it, so i need somthing bigger! im looking for at least 500 gig, maybe 750, maybe 1TB. i was looking as some, and i have a few differnt brangs, some that i havent heard of, here they are, wester digital (500 gig, $120 1 year warr), maxtor (500gig $100 5 year warr.) titanium II (500 gig, $120) western digital (750 gig $180) seagate agent (750 gig, $180)  lacie (500 gig $170)

what do you think?