First things first – if you aren’t currently using source control or are still using something like SourceSafe – stop! Read this article from Jeff Atwood, and come back.
Team System is a great option for larger companies with the budget for it, but for most shops subversion is the perfect solution. Set up your subversion server, and on the clients use TortoiseSVN to integrate subversion with the shell.
While merging can be relatively painless with Tortoise, too often people forget to get updates from the repository often, which can lead to subtle bugs during development. Fortunately Tortoise comes with a command like interface making it easy to automate this process. Simple create an old-fashioned batch file with notepad in your StartUp folder, and add this line:
TortoiseProc.exe /command:update /path:”c:\path\to\your\code\” /notempfile /closeonend:1
Yes, the /notempfile switch is required. The /closeonend:1 will close the dialog automatically if there are no errors. For other options, check the documentation here.