You can disable all Windows Notification Ballons if you wish:
Open up regedit.exe through the start menu search or run box, and then browse down to the following key:
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
Right-click on the right-hand pane, and create a new 32-bit DWORD with the following values:
Name: EnableBalloonTips Value: 0
You’ll have to logoff and back on in order to see the change… or to be more correct, you won’t see any popup balloons anymore.
Source: How-to Geek
Actually, you need not do a registry hack. It's as simple as right-clicking the system tray and disabling all notifications from the programs on the system tray.