The notifications are called "balloon tips". If you disable them
globally, you will not get any and as you say, some are useful.
Try this: right-click the wireless connection icon in the taskbar and
click "Open Network Connections"
In the Network Connections window, right-click the Wireless Connection
and click Properties.
In the Wireless Connection properties, uncheck the box for "Show icon in
notification area when connected" and click OK.
The wireless icon should no longer appear and hopefully that will
eliminate the balloon tip.
I have found the network icon setting to be buggy in XP, and unchecking
the box does not always get rid of the icon, but it is worth a try.
MS MVP Oct. 2002 - Sept. 2009