To extend the signal strength of a Linksys WRT54G router (all versions excluding v8 – they no longer let you replace the antenna) you can use this adapter & antenna combination:
Ideally you would also install DD-WRT and boost the power setting up from 75mW or whatever the default it. 110mW tends to be a safe number.
If you are starting from scratch, or have extra funds, I would recommend using the Buffalo WHR-HP-G300N. You can use the same 9dBI antenna without the adapter.
To extend a wireless network wirelessly you need a couple parts:
and then follow the guide here http://www.wi-fiplanet.com/tutorials/article.php/3655041/DD-WRT-Tutorial-5-Wireless-Repeater.htm
from:
I grew tired of staring at the beach ball every morning so I decided to do something about it. I long thought the culprit to be flash based content; through my research to disable Flash I discovered the ClickToFlash Safari plug-in which gives you the option to view the flash based content on demand rather than having it pre-loaded. Some websites have multiple flash-based elements which can be taxing on memory and CPU cycles, particularly with the multi-tabbed web browsing I do. I did not want to disable all plug-ins as I like some of the Safari 5 extensions, that coupled with the fact that flash-based video is widely used.
“It sounds like a bad Application Firewall configuration (missing the exceptions that allow configd, mDNSresponder, and racoon). Restore from the defaults:”
Open Terminal and type the following:
sudo cp /usr/libexec/ApplicationFirewall/com.apple.alf.plist /Library/Preferences/com.apple.alf.plist