The first thing to find out is the spec of your current ram.
I think yours is SO-DIMMS which I believe is all 200pin. I'd double check with your documentation to make sure of that.
Then check it's frequency and cas latency. The first number will be 533mhz or 1066 or some similar number. The second will be a single number like 4 or 5 or the full latency represented as: 4-4-4-7 or 3-4-4-7 or something similiar.
If your PC ram has the same frequency and cas latency as your mac ram your good to go. If not, I'm not sure about Mac Bios, you can change the settings in the bios if your mac gives you the option. If it doesn't your SOL and have to buy ram that is the same as what you got or junk what you have and buy all new stuff.
However there is always the off chance you can plunk in a stick of ram with different cas latency OR frequencey and still have a stable system. I won't hurt your system. It can't destroy or fry anything, it can only cause instability. If it's stable kudos... if it's not see above.