I have a laptop with a wireless adapter that connects (12MB/s) to a wireless router connected to cable internet. In order to get a decent wireless signal, the laptop is in a location inconvenient for me to work. My comfy cushioned chair is in front of my desktop WinXP box, which has a cellphone internet connection (16KB/s) used exclusively for one application. The desktop has a LAN connection to the laptop. With the cellphone connection turned off, and using XP Internet Connection Sharing, the desktop plays well with the laptop's 12MB/s wireless/cable connection. My question: is there any way to keep the dedicated cellphone internet connection running for the one application, and to use ICS through the LAN adapter for all other internet apps? The cellphone internet connection must stay isolated from the internet connection on the LAN. The proprietary app uses one user-specified port, say "nnnn". My idea was to open port "nnnn" and close all others on the Windows Firewall for the cellphone connection; also to close port "nnnn" and open ports 25, 80, 443, on the Windows Firewalls for the LAN adapters on both machines. I welcome suggestions as to how I can use the dedicated cellphone internet connection on the desktop simultaneously with the cable connection on the LAN. Otherwise, I suppose I can always fasten a chair to the top of a six foot stepladder...

You're never going to split the OS that way. How far apart are the laptop & the router, that you can't move the laptop?

The wireless router is about 100 feet away in the house next door. The adjacent corner of my house is the only place where my laptop will pick up the signal, and the signal improves nearer to the ceiling. A 25-foot Cat5e ethernet cable connects the LAN adapter on the laptop to the LAN adapter on the desktop. When I try to run both connections at once on the desktop, the first to connect locks out the other connection.

Your first post didn't say anything about the internet coming from the next house. That's a hard way to go as is ICS. You really need a decent connection coming directly into your house. How do you know if a politician is lying? His mouth is moving.