Internet Connection Sharing?

I have a desktop and a laptop. Desktop have ethernet and lap have ethernet and wifi.i have broadband and its modem is also acts as wirelessrouter. so i have connected my desktop to that modem through ethernet. i have broadband bridge connection so i have to dialup the connection. i need to use the internet through my lap. when i connect to the wireless network it gets connected but i cant dial the connection because i have already dialed from the desktop. how can i share the internet connection meanwhile i need to access the desktop files through the router. both have windows 7 installed Pleas Help i dont have knowledge about networking