After looking at the AD script earlier someone has pointed out a Free IT management suite.

You can get it from here - [1] http://www.spiceworks.com/

There are sponsored links within the app however if it does the job.

-Update-

The software looks very professional and collects some excellent information about my office network.

I asked it to product an excel report however and it stuck at 100% CPU for an hour and managed to use 2gb of ram before I stopped the process.

It may be time to run a smaller report