Media Disconnected (Windows Vista)

My internet randomly stopped working in my desktop computer, running Vista. My computer is directly connected to the cable modem (no router). After troubleshooting and contacting the internet provider we verified that it is 100% not the cable modem or the cable itself (I connected it to my xbox and it was fine).

After doing an IPCONFIG, I keep getting ''media disconnected''. I made sure to update the drivers (have internet at work). Still ''media disconnected''. Figuring that it must have been a hardware problem with my NIC I figured I would need to replace it. The problem is I have a crappy HP and I don't see a slot on my motherboard for a internal card (the current NIC is built into the motherboard).

My next course of action was to buy a temporary fix in an USB to RJ45 adaptor. After buying and installing the drivers I am still unable to connect to the internet. After verifying on the phone with the adaptor people, it was deteremined everything was installed correctly and it should be functioing correctly. In device manager everything seems to be ok, as my initial NIC, wireless, and now the USB to RJ45 connection all seem to be showing up.

My comptuer does have built in wireless, so I have purchased a wireless router (linksys) in an attempt to circumvent the hardware. The problem is I need the internet in some capacity to set up the wireless for the first time.

I am fairly inexperienced with this sort of stuff, as you can probably tell. I am really at a loss here and any help would be very much appreciated.