According to most of the sites I went to (like the one below) it states that it is expandable up to 2 gigs...I believe that means there's only two slots..Installed memory 512mbCheck how many slots you do have.
Get whatever you like but be sure that your ram is coming from the same manufacturer otherwise your other stick might not work with the other.
James
website-http://www.dealtime.com/xPF-Hewlett-Packard-Pavilion-Desktop-with-AMD-Athlon-XP-Processor-3000-a420n
Somewhere I saw something about going into bio's and it telling you what memory, and how many slots and what not....If you tell me how to enter bio's I'll do it...
I think it was hit F1 while booting up but I'd like to be sure...thanks