how to build a tool to view cpu usage & free space in drives for servers?

You are right, but OP would need to build it using WMI. If you simply show the sample lines of code, it would make a good answer (but I already did it in response to some past question).
--SA

'Scriptomatic' does it. It's a free download!
http://www.microsoft.com/en-us/download/details.aspx?id=12028
http://technet.microsoft.com/en-us/library/ff730935.aspx

Very useful links. I would gladly up-vote your post if it was an answer.
--SA