If your network doesn't have any shared storage, I'd also recommend
Dropbox. (Full disclosure: that's a referral link. Just hit dropbox.com if you're opposed.) We set up an account and put the software on all the computers in the showroom. I put in the files (CARFAX, GM Global Warranty Management printout, vehicle build, shop bills), they sync automatically out to all of the computers. There's some mild griping that Dropbox puts out an alert when new files are added, but they also say that's how they know I'm working.
One thing to note is that I had to call our web filter company to get them to whitelist the site; your mileage may vary.