Installing mac on external hdd?

Hi,
As I did not find any specific group for this question, i am putting it here.

Can I install Mac OS on an external hard disk?

Is this possible or not? I know it is very hard to install mac os on non-mac hardwares. I have a dell inspiron laptop and i want to use mac from external hdd.

plz suggest.
thanks
sk

It violates the licensing to install Mac OS X on non-Apple hardware, IIRC.

However, on my MacBook Pro I have installed Leopard on an external (firewire) drive without any problem. Probably doesn't help a typical Windows user...