Then I would say get a new router.  Honestly even a cheap $30 router by any of the major brands (Dlink, netgear, etc) will have solid DHCP reservation support these days.  Just check the reviews on a networking site before you buy one to make sure it will do what you want it to do.

For example:


Grr..  bitcointalk's image proxy is broke.

Direct link:
http://i.minus.com/jZPw0b7bBMH99.png

I have 8 computers and many other IP based devices on my home network and couldn't live without DHCP reservation. I've been using it since routers starting using it and I've never hard coded an IP stack since then. I highly suggest everyone does this that has this ability, since once you go that route it's pretty much trouble free. Let your router do all the work, not you.