Okay, and chances are that's an Intel mobo in there as well, so....
1) With 2 slots, you're most likely only able to max out at 512MB of RAM, so buy two 256MB sticks.
2) Try and find out what model Intel motherboard you have (are there any stickers on the mobo itslef that tell you what model it is?).
3) Go to Intel's website, search the motherboard section for your model, then click on the link for "tested memory".
You should be able to find a list of all PC2700 RAM that has been tested and/or certified to be used with your board.
If you can't find out what model your motherboard is, then you should at least be safe with Kingston RAM... that's usually guaranteed to work with all Intel mobos.