SBC software - How to update

Howdy folks,
The wife finally reinstalled SP2 and now has "limited or no connectivity" on her internet connection. Her machine is a Dell Dimension 4300, CNet Pro 200WL PCI fast ethernet adapter, Linksys BEFSX41.
She has talked to dell and linksys and has gotten no-where.
An earlier post on this subject suggested updating SBC software. I understand SBC means "single board computer", but what kind of software is it, and how do I update it?
Thanks,

 

Thanks Halo,
will give it a try. Its been a nightmare.
Kevin