Sooo...do you have a cable, DSL, or dialup connection to the Internet? Is the Internet connection working properly...or is the LAN aspect (home network) the only aspect you have problems with?
What do you mean that the system cannot detect a LAN? Did you set up the LAN from scratch?
Did you check Device Manager for possible clues on each system? Is the network adapter on each system reflected there?
Did you try running the MS/XP Network Wizard to reestablish connections?
Are you using a router?
I guess I don't understand...why you feel like you have to switch connections...when it seems to me that setting up home network and using a router would accomplish what you do manually.
What does "None of the microsoft wizards seem to work." mean? What wizards exactly, please?
You already checked all connections and did a check for possible malware interference?
Did you check Event Viewer for possible clues?
How To Use Event Viewer - http://www.bleepingcomputer.com/forums/t/40108/how-to-use-event-viewer/