I have had good luck using a starup script to install Office with Group Policy. I usually create a seperate OU called "Software Install OU" just to install software and then after that move the computer to appropriate OU.
1) Configure the "Software Install OU" GPO as follows: Computer Configuration\Policies\Scripts\Startup. Create a file and name it something like office2010install.cmd. The contentents should look something like this...
\path to office2010share\setup.exe /config \path to config file, this depends on type of office install Standard.WW, ProProPlus.WW, or Enterprise.WW\config.xml /adminfile \path to Updates folder\office2010.msp Copy this file to the the "Software Install OU"
2) Use the Office Customization Tool to create a Custom Office Install file (MSP) name it office2010.msp. Place it in the Updates folder in your Office 2010 Install Share. At very minimum put in your product key, accept the Lic. Agreement, and Display level to None.
3) Customize your config.xml. This depends on which type of Office you want to install. Need the following information in your config.xml
Place it in the appropriate folder such as Standard.WW, ProProPlus.WW, or Enterprise.WW
Test your work. You can always just run the office2010install.cmd locally on a computer to make sure this works. Then move on to testing the OU install.