Think of an AP as a switch with a radio antennae. Think of a wireless router as a router with a radio antennae.
The AP is a layer-2 only wireless switch.
If you PC's are all in the same network then a wireless AP is OK.
If you have a xDSL connecttion and want to use it to connect to your clients, then a wireless router/gateway is the way to go.
If money is no object, then I recommend a wireless router/gateway. Most wireless router/gateway has a built-in 4 (or more) port switch anyway.