Without knowing the exact chipset you are using on your NIC, it is difficult to find a driver. A few google searches hinted that your 4300 uses an NIC with a 3Com chipset.
According to this thread
, a 3Com driver downloaded from this site
was able to get their 3Com network ethernet card working under Vista. If it works in Vista, it should work in Win7.
Otherwise, you could buy a more modern $10 NIC
and install it in your neighbor's computer and solve the problem that way.