Today I needed to do an audit of a server remotely that I know nothing about. A work college told me about Belarc Advisor - I ran it on the server remotely. I was very impressed at the information it was able to provide me with - even serial numbers which is excellent if you ever need to provide vendors with this information.
Belarc Advisor is free software and can be downloaded from:
Here is an example of some of the information it can provide you with + much more: