Update: 01/28/2009
Before you venture off this way, let me give you a bit of advice that may save you some time and frustration. If you can, take the 7.2 router back to where you bought it. If you have a family member or a friend of a friend who needs a new router and doesn't need the dd-wrt stuff, give it to them. Then, go out and buy a Linksys WRT54GL. These are the Linux based routers Linksys released that support third-party firmware updates. They are technically a re-release of the v4 WRT54G. I found out about this a while back and have been very happy since.
A few months ago I gave my old Buffalo (WHR-HP-54G) router to my uncle in law. A few days later I went online to purchase a new router and was very disappointed to find out that they were temporarly unavailable in the US. Since I could not buy my favorite router, I decided to use an old laptop and try out IpCop.
I must say I was very pleased with IpCop. The installation was quite smooth even on an old notebook with PCMCIA cards. Unfortunately, after some time of testing, I decided to go back to DD-WRT. The notebook was just too old and too run down to run reliably, so against my better judgment I bought a Linksys and got DD-WRT back up and running.
I bought a WRT54GS (WRT54G with SpeedBooster) from my local WallMart. (I happened to see it while I was browsing around in the electronics section and it was priced relatively low ($59), so I decided to give it a try.) I wasn't sure if that particular model was going to run DD-WRT, but I took it home anyway. (I felt pretty confident I could get the original firmware back on it and take it back if I didn't like it.)
When I first opened the box I was little worried as the version number on the bottom of the router read v.7.2. I had never seen this in any of the routers, but a little search on the internet revealed that 7.2 was most likely a "quick-fix" release to version 7. I went ahead and followed the instructions for loading DD-WRT on a v7 router. (DD-WRT's wiki does not list the version 7.2 on their compatible devices list. Technically, one could say v7.2 is a version 7, but I'm pretty sure they would have the specifically listed it, so I'm going to assume they don't know if it works or not.) Everything installed ok and I'm now an "almost happy" owner of a new Linksys router. I still don't like that Linksys crippled their WRT54G/S.
So, if you need a new router and happen to find a Linksys WRT54GS with serial starting CGNE, then you can flash it with the latest release candidate of DD-WRT. Below you will find the links to everything you need for this specific version of the router.
INSTRUCTIONS
VXWorks Killer
DD-WRT Micro