AOL say that because they want to charge you an extra £6.99 a month to support their wireless router. (Not any that you buy) I`ve done it by using a DSL-G604T router from here click here It has a USB adapter included in the bundle for the upstairs computer. The other one can be connected using a cable to one of the ports on the router or by buying another uSb Wireless Adapter.
There are plenty of other modem/routers on the market. Have a look at the other thread about advice posted this morning. One thing to note about AOL when you have the wireless set up - only one computer can log in to AOL at the same time. The second computer ignores the AOL log in process and simply opens Internet Explorer for an immediate connection. If two computers try to be logged on to AOL together (Using the same screen name and password AOL spot it and disconnect both.) No great shakes really! Just make sure you know if someone else is already logged in.