First thing I would recommend reinstalling the Proxy Settings; by removing them in the Add/Remove Application Tool on Windows Options. Uninstall all Internet Options, including Internet Explorer, then reinstall them - make sure you have your Windows CD before this. If that doesn't work - try using the ISP's CD to install the Internet Connection itself.
On that; its really not worth the Wireless Bother just for a Dialup connection. I would recommend buying some phone cable and running it up to your room.
A Knight is sworn to Honour. His heart knows only Virtue. His blade defends the helpless. His might upholds the Weak. His word speaks only truth. His wrath undoes the Wicked.