Is that the IP address from the XP machine? That's an external IP address, like one that is handed out to a router. I forget, you do have a wireless router, right? What kind, or is the modem the router?
Well the problem is you're going out on the internet then trying to come back in. The Insight router is handing out external IP's. Either the port on Dell's firewall must be opened, or the port on the router must be directed to the Dell. Unless you have a very secure password I would be careful of either. Since you can't even get to the router there's nothing I can do without knowing what kind. Then you'd have to know the password to get into it to forward the port to the Dell.
How do you connect with the Touch, is it an IP of 74.x.x.x? Don't post it, only the first set or two of digits.
Did you set the firewall in XP like in the directions of the first link I posted? If so then the problem is in the router/modem or whatever it is, it would need to be set. Again, if you can't get at it or configure it there's nothing we can do.