I'm also a broke disabled person using an old laptop with a dead screen; mine is a 1.6GHz that I upgraded to 1 GB of memory with a $5 stick from eBay a couple of years ago.

What really matters isn't the distro itself as much as the desktop environment. (99% of distros are completely free, so that's not an issue.) The easiest approach would be to download one of the live CDs that are hosted directly by a lightweight desktop team -- the two I know of that have some of their own CDs to download & try out are LXDE and Trinity.

When you've gotten used to whichever one you end up using, and feel like you want to try something new, you'll almost certainly know enough about Linux to figure out what to try next. Good luck!