XP to XP Printer Sharing Problem

A peer-to-peer network based on a SOHO router w/4 - 802.3u ports.
Router is also 802.11g and WiFi is enabled (WPA2-PSK-AES).

A Win XP Pro SP2 Desktop with USB-attached SHARED printer connected to
the router using 100BaseTx connection. User's "My Documents" folder
is also SHARED. Simple File Sharing is disabled.

A Win XP Pro SP2 Laptop with proper WiFi adapter connects to the LAN.
Same user id and password on Laptop as Desktop. Simple File Sharing
is disabled.

Printing to the shared printer from the laptop doesn't happen.
Printout seems to go off into never-never land.

Laptop has a Shortcut on its desktop that specifies a UNC path to the
shared "My Documents" folder. Double-clicking on this shortcut causes
a credentials pop-up to appear, and -- when credentials are entered --
the shared folder opens in a Windows Explorer window. At this point,
printing to the shared printer will occur without trouble.

It IS true that it takes some time for the laptop to negotiate a
connection to the network -- the network drivers seem to be just about
the last things to get launched. It IS true that the laptop user logs
into his session long before the connection gets established. It is
also true that there are several WiFi LANs in the neighborhood which
can be "seen" by the laptop but I believe the connection is being made
to the proper network automatically as a matter of preference.

Still, I'd expect that he should be able to connect to the desktop
without having to enter credentials and that he should be able to
print to the shared printer.

What am I missing here?

Thanks....
--
BilBo