RJ45 wireless?

I refurbish older computers for needy students. Now I am working on an x86 laptop (IBM Thinkpad) that has only an RJ-11 port and one USB port. The machine's OS is Windows 2000 Pro. I got an adapter that connects to the USP port and gives me an RJ-45, and it works well. But the user will need a wireless connection (the family is not well off and must reach the internet via a neighbor's wireless router). The Thinkpad claims to have an infrared 'wireless' connection but I have not found it. I would not know how to use it if I did find it. I've tried 2 different USB- to-wireless adapters but neither can 'see' my wireless router 2 feet away --and, although the drivers do install when I tell the PnP Wizard 'this is it' then it claims they is no driver present. The router and adapters are all 802.11g. Has Tom's got something at a low cost to do this job?