You need a KVM switch (keyboard, video, mouse) that connects one set of bits to two or more computers. Buy a simple one that includes a set of cables and you can dance between the two by touching a button. KVM's go from super simple and cheap to top end devices for controlling hundreds of PC's in a server farm.
The cordless bits should plug into the sockets on the KVM.
You can share the broadband either through a modem / router or a simple peer to peer network if you have LAN adaptors on both PC's or are willing to fit them. This site is full of advice and how-to's for this as is the web in general.