CodeTwo Outlook Sync Free is a simple tool which quickly synchronises your default Outlook calendar and contacts folders between two computers on a local network. And so if you've been away with your laptop, for instance, connect it to the same network as your PC and you'll quickly have the two back in sync.
The program is easy to set up. Install it on the first computer, you'll be prompted to install it on the second, and Outlook Sync will then walk you through the process of setting everything up. It's generally quite straightforward; take a look at the online manual if you'd like to see what's involved.
And once everything is configured then synchronising your systems is as easy as clicking the Sync button. This even works if your PCs have different versions of Outlook: there's official support for Outlook 2003, 2007 and 2010, but the program should also work on Outlook 2000 and 2002 (although CodeTwo no longer offer technical support for those versions).
Please note, CodeTwo also produce a commercial version of Outlook Sync with many more capabilities. It can sync your email, tasks, documents, and any other calendars and contacts folders you might have beyond just the defaults; and you've the option to do this automatically, too. The program is priced at $59 and the CodeTwo site can tell you more.