Replying to Wanna help me out with external harddrives? +k

my macbook is 100% full so i need an external, so i headed up to circuit city, just to see and the external were like $150!? wtf?

so i o home and hit up google, and found some for less than that, so ive got a couple questions here;

whats the differance between them? other than space and cost?

andddd do some work with macs while others don't? and how can i tell?

i found this, any opinions?