Which type of hard disk .i should buy.?

i am planning to buy external hard disk....
which type of hard disk ...i should buy..??
with external power or Without..??

some of my friends say that hard disk needs more power,,,so
above 1 TB hard disk needs more power..so better to buy HDD with external power...

i am confused...???

This actually depends on you. If you feel like you are going to need more than 1 TB of space, then go for it. I personally would get one of the more portable ones. Less space, sure but they are lighter, don't require an external power source, and come with sweet little cases that you can buy! haha