jetflo19,
Yes, it is called MAC Address filtering. The WiFI address is the address you would use. Depending on your router you may need to replace the :'s with -'s.
However, without other security your network may still be vulnerable. Many implementations of MAC Address filtering allow computers to join the network, but not get DHCP.
So I would still recommend using WPA if possible, and WEP at the least.
Hope this helps,
Nathan C.