for general info about your motherboard and here
to get a pointer to BIOS and Driver downloads. I would leave your BIOS alone for now. It worked before; it's probably fine for what you have. The LAN drivers for that board should be the Via 8237 ones at this link
. Just scroll down until you see the VIA 10/100 LAN Drivers for VIA VT8231/8233/8235/8237 Intergrated LAN Motherboard.
Once you get your LAN working, you might be able to use Windows Update to get the USB drivers you need. It's a bit odd that those didn't work right away, but I did note a VIA USB2.0 Patch (Under WinXP+SP1) here
that you might need as well.