Well after experimenting with many firmwares for the WRT 54GS v1.1, especially Openwrt (openwrt.org) i finally bricked my router. Bricked = cant talk with it any more, no telnet, ssh or ping. I then searched on how to unbrick it i came up with the following solution that worked for me:
1. Un plug router
2. Open router and find the INTEL Chip. Mine was ver. 3.37.1. (this will void warranty)
3. Find pins 15 and 16, not on the chip itself but the solder points nearby. They have little white lines every five pins next to the points.
4. Short pins 15 and 16 with a small deivce, i used tweasers.
5. Start a commmand window that continuously pings the router (default ip of 192.168.1.1 - "ping -n 100 192.168.1.1")
6. Plug router in, when you start getting replies from it then remove short between the pins. The power light may flash and the DMZ light may also flash at a slower rate.
7. Run your favourite tftp prog (XP and linux have native ones) and upload the firmware. Dont reset or power cycle router after the shorting of pins and the subsequent ping replies.
Linux command line:
tftp 192.168.1.1
binary
rexmt 1
trace
put firmware.bin
Windows XP:
tftp -i 192.168.1.1 put finware.bin
Fimrware.bin is the firmware you wish to upload, it doesnt have to be called firmware.bin. Just type what ever it is called. Make sure you are in the right directory when you do the tftp bit.
After a few seconds of flurry on the eth light you should get a message to say a "firmware was upload in 6 seconds" or similar. Let the router settle for about 2 mins, the power LED should stop flashing, then log in via web interface.
Bobs your uncle.
Wookie