NF7-S revision 2. Do NOT get the NF7-S2 or the NF7-S2G because they do NOT provide overclocking facility.
Throw away the PC2100 RAM because it isn't adequate. You need to push Fsb up towards 200MHz to overclock it, so you need PC3200 or better RAM. If your chip runs at 200MHz fsb it will effectively be a 3200+. I have two here which run at that speed, but I'm not sure if yours will be suitable. You'll have to try it and find out!