Those boards were usually SD-RAM, instead of the newer DDR.
You can take out one of the modules, and look at the label
(they should be labeled as to whether they are SD or DDR). It's possible that you have Rambus memory also.
Even if the label is unclear, you should be able to tell by looking at the number of pins (don't worry about counting them).
If it has 168 pins, in 3 different sections, like this one:
It is SD-RAM.
If it looks like this (only 2 sections of pins, 184 total):
It is DDR.
If it looks different, take a photo if possible, and we'll tell you what it is.