You should be able to see if it is PC100 or PC133, but I don't know of anywhere in the bios or even in Sandra that tells its Cas2 or Cas3. I know you can set which it is in the bios. I guess you could set your bios to Cas2 and if you computer starts up, its cas2, if it just continues to reboot and never makes it to windows or if you get some kind of error message, then you have cas3.
Just a thought.