I'm planning on getting one of these:

http://www.tranquilpc-shop.co.uk/acatalog/BAREBONE_SERVERS.html

5 drive-bays, Dual-core Atom, 2GB RAM, nice and silent etc.

Take your task seriously. KPI (Key Performance Indexes) are a great way to prove your worth to the company. But instead of just concentrating on the obvious, how fast is service X, what is the service level/uptime on service Y etc try to create another metric that captures the other side of the coin. What happens if you fail? You now have an opportunity to provide data on how important your contribution to the company is - sure, as others have mentioned, you aren't making teapots or cars but if you fail - how many teapots or cars aren't made? How much does the company loose? What is the probability of failure currently and how could you improve it? These are tough things to figure out but if you can - the beancounters will love you.

For instance, begin from just simply calculating the average income per hour per user, this is the absolute minimum the company looses if they are unable to work. How long will they be without computer services if something catastrophic happens, do you have plans for this catastrophic event? How probably is the event?

Begin from there and tell a story about how you are a productive part of the company by enabling them to do their job.