OS X Server

I am working on setting up a small network with several of my work computers, all Mac Pros going to a gig switch and working great. On this same network I have a 17" MacBook Pro with a Promise Pegasus raid plugged into the MBP via thunderbolt. The laptop is running plain lion. My question is this, why would I want to use os x lion server instead of just plain lion on the MacBook Pro. what features does lion server give me that normal lion doesn't?

We are just using that MBP as a way to see the raid on the network. it isn't really doing anything besides being another computer for someone to work on. My concern is that two people might try to access the same file at the same time and that might cause the system to freak out.