Hi all!!

I need some advise on laptop external hardisk. Not really sure where to post so I thought of trying my luck here. If this isn't the correct place, admins please move the post

For external laptop hardisk what brands should I be looking at? And I understand that not all casings support every hardisk capacity. Meaning a casing that can support 30GB may not be able to support a 80GB hardisk right?
Any other things I should be wary of?

Thanks!