Do you see any device with yellow exclamation mark in the device manager of Window XP?
When you installed the drivers, did you follow the installation instructions? The initial setup extracts the package to a location on your hdd and does not install any drivers, you would need to go to that location to manually run the second setup in order to install the drivers. In addition, are you sure you installed the right drivers from lenovo webpage? because there are drivers listed for 3 different wireless adapters, you can have any of one.
Also, when you turn on the wireless through the switch on front, do you see the wireless status indicator light near the touchpad buttons blink? It looks something like this ((((l)))) . Since it's unclear from your post how you downgraded to Windows XP (lenovo downgrade media or retail copy) so I don't think asking what happens when you press Fn + F5 will do any help here but you can give it a try too.
Moreover, by chance did you install Access Connections along with wireless drivers?
For fingerprint reader, I suggest you install the following patch:
Patch file for Lenovo FingerPrint Reader for Windows Vista, XP - Lenovo 3000 Family notebooks.
Then configure fingerprint logon settings through the Control Center.
You can also give
ThinkVantage System Update a try, it's going to present you with more latest drivers.