There certainly aren't many (if any) routers that support USB modems, so its probably best to get a router with a built modem. As far as I'm aware you couldn't use the PCI in anyway with a router.
The other option is to put a wireless card in the other PC as well, and then use an Ad-hoc network and use Internet Connection Sharing, making use of the USB or PCI modem without the need for a router. Obviously this way will work out cheaper but will mean that you'll need the computer with the modem, on and connected to the Internet for the other computer to have access.
The range of any WiFi devices should suffice unless the PC are very far apart.