I'm embarrassed at my own ignorance.

I have an older Dell laptop that generally fits my needs (internet, email). Unfortunately, it has a small hard drive and I'm just about out of room (even after defrag).

It's too old for me to consider paying someone to add memory, but I don't really want to get a new machine just for that. I've been looking at portable backup drives (WD, Iomega, etc). Then I noticed another thread about SSD drives.

So: what's the functional difference between them? what would be best for my purposes? Because I want the extra storage for photos (and some music archives), speed isn't as critical as it might be if I needed storage for additional apps. Looking ahead, I think I want at least 160GB, maybe more.