Open it up, look at the current memory sticks, they may say either DDR, DDR2, or SDR on them. That or if you really knew alot about computers you could tell by the pin amount and placement on the slots.
Only problem with doing something like that is that some, and alot, of factory computers wont say much about them in those programs. The best way, if its a factory computer, is to look it up on the companies website or maybe google.