You posted in the support forum for the Apple wireless routers....the AirPort Express, AirPort Extreme and AirPort Time Capsule......the products pictured below
We are not sure how your question would relate to one of the products shown above, but will try to help.
When you say that you have tried other strategies, we have no idea what those might have been.
The wireless network settings on the old MacBook may have become corrupted. To see if that might be the case on the MacBook.....and if you have not already done so......
Open System Preferences (gear icon on the dock)
Open Network
Click on WiFi on the left to highlight it
Click Advanced over on the lower right of the window
Click on the name of the HomeHub wireless network to highlight it
Click the - (minus) button at the bottom of the connection list to delete that connection
Click OK
Click Apply
Now click on the Finder icon on the dock (the smiley face)
Open Applications
Open Utilities
Open KeyChain Access
Locate the listing that contains the name of the wireless network
Click on that listing to highlight it, then click the delete key on your Mac
Close the windows
Now restart the MacBook and try to connect to the network again. You will need to select the network and enter the password to connect.
If this works, then you are all set. If it doesn't, you really should post your question in the Leopard (10.5.x) or MacBook support forums linked below for a more informed answer.
Mac OS X v10.5 Leopard
MacBook (13-inch, 2006-2010)