a nat router + a switch + a wireless access point (AP)
what you really need is just the AP.
If you don't what share your files with your roommates, and you do not care about the network performance in your house, use the "cascading" method. This way your wifi is further behind a firewall. it is easier for you to access other ppl's comuters in the house but difficult the other way around.
The second way is use a cross-over cable connect a lan port on the wireless router to one of the lan port on the wired router, leaving the wan port of the wireless router unused. this way all client computers are on the same network. there is no problem sharing among all computers in the house and speed is fast.