If you have only 5 users, and you only want to share files, why not look into Windows Home Server. It takes a "village idiot" to set it up (see last post!
I would suggest purchasing the "MediaSmart Server sold by HP, with Windows Home Server (WHS)pre-installed. Add a second hard drive for the equivalent of RAID 1 redundancy.
An added benefit is that you can back up each of the 5 workstations - in their entirety - onto the WHS, and it backs up any changes every night!. If one of them self-destructs, you can restore from the WHS (provided it's the same hardware) operating system, files, programs, desktop wallpaper - the whole shot!. This whole package will cost you less than $700!
BTW, I am using WHS with several of my Small Business Server clients to back up critical workstations. Already used this twice to rebuild workstations in about 20 minutes vs. 1.5-2 hours to reload XP, load and tweak all programsw, re-build all special mapping, settings, Outlook shortcuts, Internet favorites, etc.
Hope this helps.
Bob Hood
Hood Consulting Group