new to wireless - 4 port switch and Wireless Access Point?

Hi

I currently use a firewall running unix with two ethernet cards, one
ethernet card connects to the cable modem and the other connects to the 4
port HUB. The 4 port hub provides internet access via the firewall for my
main PC upstairs (static ip), a computer downstairs for playing MP3's
(static ip) and my laptop (static ip) using CAT5 cable.

I would like to replace the 4 port HUB with a wireless access point? but im
not sure if such a product is available for my requirements. I want to plug
my main PC upstairs into the Wireless Access Points 100mb/switch (CAT5
cable) and connect to my unix firewall (CAT5 cable). I then want to buy a
wireless PCI card for the MP3 PC downstairs and wireless PCMCIA card for my
laptop.

I heard good things about the USR 125/mb but don't mind spending a little
more if these new MIMO wireless products are better. Any ideas are welcome
on a good solution.

thanks in advance.