Upgrade Hard Drive on Armada 1750?

Hi,

Someone in this group gave me some good instruction on upgrading the Armada
1750 that someone had given me. I upgraded the memory and now have 192 mb.
That was easy, but I'm not confident enough in getting the right hard drive,
say from eBay, or elsewhere because I'm not familiar with laptops at all. I
need a hard drive that will fit, of course, and there seems to be more than
just the HD? Like I see cover for hd, or enclosure. So if I want to
upgrade the hard drive---I don't know exactly what size ( physical) drive
and I also have to get a cover of some sort?
Any advice or opinion is most appreciated. I'm trying not to spend too
much money on this as I don't have it----and I plan to use it for fairly
simple chores and email/ internet tasks.

Thanks,
Al