What coincidence! I have a Fujitsu P-2120!
Go to
www.fujitsupc.com, click on Accessories and then Memory. Fill out Notebook, P-2000, and P-2040, and you're there.
You can add another 128MB of memory to your machine for $55... same as mine. Installing it was pretty straightforward, and they were quick on shipping, too.
Unfortunately, no one else makes these micro-DIMM memory cards, so you're stuck with the manufacturer or getting one custom-made.