It is sometimes necessary to have computers with Static IP even if you are under DHCP, one such instance is when you are doing port forwarding to a machine for some application.
The Linksys WRT54G2 does not support DHCP reservations (A mechanism by which you can lease predefined IP to client computers based on their MAC address)
However, a workaround is available.
In the Basic Setup page of the WRT’s administration webpage,
Enable DHCP and specify a DHCP range by giving a Staring IP Address and the Number of DHCP users. (say, 10.0.0.2 and 100). The remaining addresses [ie 10.0.0.102 – 254] are not used in DHCP and can be used as static IPs for client computers .
Now manually set static IPs in each client computer.
The problem with this approach is that you have to manually set IPs in each of the client computers, whereas with DHCP reservations, you just set them to use DHCP and the same IP will be leased to them automatically every time.