[iBook] Airport Card Performance

[vwmai]

Hi,

I am going to list some data points and see if anyone has a clue why 
what's happening is happening.

Wireless router - Belkin F5D7230-4 ver. 4001

Machine 1
G4/466 Digital Audio
Connection via ethernet cable to router
Performance +/- 5000 kbps

Machine 2
G3/233 iMac Rev. B (bondi)
Connection Belkin USB network adaptor F5D705 ver. 2000
Uses most up to date Ralink drivers w/Ranlink wireless connection 
utility
Performance +/- 4500kbps
location 40ft from router and through various obstructions

Machine 3
G3/900 iBook
Connections Apple Airport Card (11b)
Performance does not exceed 3500 kbps despite proximity of the iBook to 
the router

Testing using other routers.
I have visited the homes of two friends. Each has an apple iBook and 
uses an Airport Express. At each of those locations I can use my 
iBook/Airport card and achieve 5000 Kbps even outside of the their 
house.

The conclusion that I have come to is that the Airport card and the 
Belkin wireless router don't get along all that well but I can't figure 
out why. I should probably load up the Ralink drivers on the iBook and 
test the USB adaptor. I suspect it will do at least as well as the iMac 
but I would like to use my "worth it's weight in gold" Airport card.

What do you think?
Chris