external vs internal HD

I have an older computer that does all I need, except it doesn't have alot of gig space, approx. 10, so I want to add more. Is an external much trouble to deal with? All I would do with it is dl and save music, movies, etc.
Sorry for such a remedial ? but I ain't too savvy about this kind of thing. Any info would be great.
Thanks!

What OS are you running? If you're using windows XP or 2000 you shouldn't have any problems. However, if it is an older computer and you'll be using a USB1 port then you're going to be held back by the speed restrictions in USB1. If however you have USB2 then you wont notice a speed difference unless you're transfering large files to and from it. The one thing about external hard drives though is that they're generally much more expensive and when you look at it they shouldn't be. Inside the case for an external hard drive is a standard IDE (internal) hard drive, that's just hooked up to the small case which converts it to a USB connection, that's it. I wanted an external hard drive so a year or so ago I bought a 200 gig hard drive and then spend $30 or so and bought a USB2 enclosure. Just put the hard drive in the external case, close it, plug it in and go. Ended up costing me about half the price of brand name 200 gig external hard drives at the time

well there you have it, thanks man!
OK now that I know this, how hard is it to change hard drives? Do I lose everything?