I have recently experienced serious problems with my Linksys AP, it constantly restartet. I have made one firmware update before and I was running the latest firmware from Linksys.
Google to the rescue...
Apparently the chipset in the Linksys is from a another vendor (D-Link) and it is possible to update the firmware with software from them, this is commonly known as the 'wap11ver22 hack', this page describes it thoroughly.
After this I also update my Airport driver and now things are running smoothly under 10.3 (for now).
