Download CUPZ from here.
Run it, and look at the SPD tab.
It will tell you how many RAM slots you have (usually 2), and what type of RAM your system uses.
Buy two matching RAM sticks (either two 1 GB sticks or two 2 GB sticks) and replace what you have.
It shouldn't cost that much. Check places like www.newegg.com.
Yes, Grace is right, but if you had more RAM, you wouldn't need to swap as much.
What processor does your system have? It would give us an idea about the age/speed of it.