Repairing a WinXP pro installation

This is a Dell Latitude C610 laptop that appears to have the Internet Explorer either removed, or otherwise corrupted(I think). I purchased a USB wireless device for it, installed it, and got as far as getting the wireless USB adapter to connect to my wireless router. It is a Linksys compact Adapter, and my router is a D-Link. The connection software installed ok, and told me that the adapter successfully connected to the network, but the Internet cannot be found. This laptop had all sorts of Netzero programs. When I opened IE, under Tools> Internet options>General, the address for the home page was not your typical http://www. comcast, or aol, or bellsouth, etc. but some cryptic line to a location in the Windows folder.
I'm at a loss as to how to proceed. I was thinking of using my Win XP pro disk to repair the installation, hoping that that would reinstall Internet explorer. Is that the right thing to do?
BTW, when I installed the software for the wireless adapter, and then plugged the adapter into the one and only USB port on the back of the laptop,and found it to not connect to the internet, I removed it and attempted to install adaware, spyware blaster, etc, via a USB Thumb drive. Windows told me that the USB thumb drive could not be read or recognized-unplug it and reinsert it. It may be defective, etc.
I had just unplugged it from my other computer and when I reinserted it into this other computer, it read just fine. I then uninstalled the Linksys software on the Latitude C610, and now it reads the USB thumb drive just fine.
Any hints, help? Thanks.

 

It sounds like the system has been "modified ", not necessarily in a bad way. Pete's advice or a reinstallation of Windows sounds good to me. If you run a reinstallation you should find that it does not state something like "all data will be lost ".

If you are not sure, backup your data anyway. If there have not been many modifications (added personal data), a "new" system would be my choice (reformat).

Matt