I am in an area with open WAPs.

Is there any way to do the following on a LAN?

PC A:
Dial-up internet with ICS enabled
Connected to LAN using ethernet switch

PC B:
Wireless internet using internal wireless card
Connected to LAN using ethernet switch

As it is, PC B connects through the wireless only when PC A is turned off or when the LAN connection is disabled. If PC A is turned on and LAN enabled, the wireless internet connection disappears.

Can I have PC B connect to the internet using the wireless connection and be able to use the dial up ICS from PC A as a back up connection?

Its going to be terribly slow on dialup to connect 2 machines to 1 dial

I realize it is slow.

I am interested if it is possible to have one computer able to use both the LAN and dial up ICS as a backup on a computer with wireless.

Well certainly, but you would need a PROXY to your other computer to use it

How to Enable a proxy on my PC