use "hardware-address" (don't put the 01 in front just the mac addr xxxx.xxxx.xxxx) for your unix box and "client-identifier" for your windows box, as far as i know you can't have both on the same "ip dhcp pool" and if you create a different pool for...

look for a transciever, like fiber to copper (ie. 100FX to 100TX), but look for 10base2 or 10base5 whatever you using to 10/100 Ethernet (i'm assuming this is what you are referring to by rj-45)