Posted on Ghacks as a way to circumvent WGA checking when installing the latest MS products for yourself but just as usefull for Adminitrators who want to deploy these products on their environment:

The last days have seen many stories about ways to prevent WGA (windows genuine advantage) checks while downloading or installing Microsoft products such as the new Internet Explorer 7 or Windows Defender. Haklabs describe an easy way to prevent WGA checks while installing .mis files.

All you need is a tool named Orca which is an official Microsoft tool for modifying and validating .msi installers which means Microsoft delivers the tool that one needs to avoid the WGA check - the irony.. Orca is part of the Microsoft Windows Server� 2003 R2 Platform SDK Web Install and can either be downloaded with the full package or as a standalone.

After installing Orca you run the software and open the installer from within. Select InstallExecuteSequence from the left pane and right-click Check WGA and choose to drop it from the menu. Save the file, close Orca and run the installer without a WGA check.

Please not that this method is not working for other kind of installers. The new IE for instance does not come with an msi installer but an exe.