How to know if processor can be upgraded

I currently have a PII 350mhz system with an AGP slot, 3-PCI, etc. I recently moved, and cant seem to find my motherboard info. I need to be reminded how to find out what type of motherboard I have so I can find out if my system can handle a fasterprocessor, such as PIII or P4. And, can this info be found out without opening the case.