How many users are you talking about?
For fifty or so, you could look at Software Installation through GPOs - I use this regularly with the ORK (Office Resource Kit) to apply a transform and deploy within an SME that has only a single office. It works remarkably well, with no steep learning curve.
For more seats than that, or for organisations where you're looking at more thyan one location, you should probably be looking at SMS or something similar. Trying to sod around with GPOs for that sort of deployment is asking for trouble - you'd need multiple copies of the same deployed package (you might be able to get away withy this by being clever with DFS), fast and reliable bandwidth if hosting from a single location instead, applying updates to the installation would be counter-intuitive as you'd need to do it in multiple locations (or it would take ages to apply to each OU if there was a single source for files) you can't report or inventory any of the installations etc etc
Here's a couple of links:
Deploy using Software Installation via GPO
Deploy using SMS
The links are for Office 2003, but should apply equally to much of Office 2007 and I'm sure you can find similar resources where the procedures differ for O2K7