If you've ever wasted time working on the wrong version of an estimate on your laptop while the right version sat on your desktop computer, you know the importance of keeping multiple computers in sync. Here are several proven solutions.

Save-N-Sync and PeerSync. Save-N-Sync is a good choice if you only need to synchronize a laptop and a desktop computer; over a network or using a direct-cable connection, you can synchronize any two files, folders, or drives that will appear in "Windows Explorer." The bare-bones version costs $29. If you'd like to schedule synchronization in the background, or monitor files in real time, advanced versions will set you back $59 and $89, respectively. Step up to PeerSync, starting at $299, to sync a whole network of users ( www.peersoftware.com).

LapLink Gold and PCAnywhere. Offering more than just remote access, these "remote control" applications let you run applications on your work PC from any Internet-connected computer. Both have secure file synchronization utilities, as well. On a fast connection, remote access can be the next best thing to being there. LapLink starts at $100 ( www.laplink.com), and PCAnywhere costs $180 ( www.symantec.com).

Revision Master. If you have multiple users working with critical files, you need to stay in sync and monitor and track who's done what on the project. Revision Master enforces a secure document check-in/check-out so nobody can undo somebody else's work by overwriting the same file name. It costs $179 per user or $449 for a five-user license ( www.nemetschek.net).

Intranets.com. If you're working with people over the Net instead of an office network, an Internet service can be your "filing cabinet in the sky." Like Revision Master, Intranets.com enforces document check-in/check-out, ensuring the most recent version of your files is always available at your secure site. The price for the service is $50 per month for five users ( www.intranets.com). --Joe Stoddard, a technology consultant to the construction industry, can be reached at jstoddard@mountainconsulting.com.