Connecting wireless to wired LAN

I have a DSL modem with built in wireless and router. I have it connected to
a switch which has a couple of desktops connected. The desktops connect to
each other and the internet fine. I have a laptop with centrino wireless and
a built in ethernet NIC. It connects to the internet fine thru wireless. I
am trying to network all three together to share one printer. I've got them
all listed under the same workgroup with different computer names. The 2
desktops see the laptop under workgroup computers, but will not connect to it
(it gives an error message that the desktop may not have permission to access
the laptop). The laptop cannot see any of the workgroup. I'm using XP with
SP2 on all three computers. I can ping the IP address on each computer and
it always gets a reply. Appreciate any help.
Thanks!