Dean,
The two previous posters are absolutely right. Running LiveUpdate will add compatibility for Windows 7 and Server 2008 R2. After running LiveUpdate, verify the version listed in the boot wizard is 11.5.1.2266. Adding Win7 drivers in the boot wizard is only necessary for the DeployAnywhere feature; for booting and Ghosting, Windows Vista 32bit drivers are the ones necessary, based on the build of Windows PE we use. Here is an article explaining:
Why does Symantec Ghost need drivers for Windows Vista when imaging some other operating system?
Thank you,
Randy