first and foremost, is the machine able to boot to a normal desktop???
if not, then you need to find a computer savvy person or computer repair facility of considerable reputation (best buy geek squad is one i HIGHLY recommend) and have them either restore the machine or wipe the drives and load a fresh install of her operating
system.
if you can load to a normal desktop, then you need to goto an internet-ready computer with a CD burner and goto http://www.belarc.com/free\_download.html download this software!! its free it works!!!! burn it to a CD, install it on her PC
install it!! run it!!! it will tell you darn near everything about the machine!! just follow the left hand collumn till u find COMMUNICATIONS and it will list any modem or NIC (Network Interface Card) on her machine like say.. "3com EtherLink XL10/100 PCI TX
NIC or Belkin Wireless G PCI Adapter ETC!!!! once you find the specific card you have, simply GOOGLE "drivers for (whatever the card is) and 9x outta 10x, you will be able to find the manufacturers drivers for said NIC and once installed properly, should
be able to access your router and internet.
i wish there was a microsoft fix, BUT, microsoft is full of software people and software people dont fix hardware. and as any hardware guy will tell ya, microsoft software is far from the best at determining hardware failures