I want to extend the existing Wi Fi Linksys WRT54G network with a new Airport express. Airport utility doesnt seem to give me the options described in various searches using airport admin utility. Any Ideas? Using Macbook pro running Lion. Router has latest firmware.
No, not in a wireless sense. The only certain way to "extend" your existing router's range is to connect it to the Express with an Ethernet cable:
http://support.apple.com/kb/HT4145
The "extend a wireless network" option applies only to Apple AirPort base stations. It will not work with other routers.
I believe you may be able to use WDS with the Linksys WRT54G but it is certain to be an exercise in frustration, even if you get it working properly.
This may interest you: http://hints.macworld.com/article.php?story=20060609053254368
Read it only if you are a glutton for punishment, or simply a nerd (same thing).
Can I extend the range of a linksys WRT54G with a new Airport Express
