Make sure that both pcs have the same workgroup name but different computer names.
Run the networking wizard on the Mesh, telling it you wish to connect another computer to the internet through this one.
Run the networking wizard on the IBM telling it that you will connect through another pc.
Make sure that the firewalls on both computers are set to allow networking.
On the IBM, open a DOS box and type "ipconfig" [Enter] It should show an ip address in the range 192.168.0.x
You should now be connected.
If you are having trouble, check the IBM wireless adaptor software that it is in ad-hoc mode.
If you want to share files between the computers, you must set file and printer sharing and then share at least one file, folder or drive on each computer.