A recent how-to guide on TechRadar, a UK-based IT site, provides a great starting point for anyone looking to set up a network that allows Windows, Mac OS, and Linux machines to share resources with one another. This tutorial relies upon three key technologies: The open-source Samba protocol (based on Microsoft's proprietary SMB/CIFS protocols); the Remote Desktop support built into Windows XP/Vista (a Mac version of the RDC client allows OS X users to open a Windows remote session); and Xming, a secure remote access client that allows Windows users to access a Linux desktop.
You can get started with the five-page TechRadar guide here.
Samba is really the key piece of this puzzle, since both OS X and Liniux use it to access Windows network shares. On the Mac, using Samba to access shares on a properly configured Windows system is extremely easy. While most current Linux distros also do a fine job of making Samba work from the get-go, others (including, sometimes, Ubuntu) may require tweaking.
Steven J. Vaughan-Nichols addresses this issue in two of his recent articles. First, on his Computerworld blog, he looks at some of the basics required to use Samba to do basic file-sharing between Ubuntu Linux and Windows systems. This post includes a link to a second article focusing on how to get Vista to work with (that is, to recognize the existence of) Samba-based network-attached storage (NAS) devices. Since an awful lot of entry-level NAS devices still seem to have nagging reliability issues, and since many of these devices rely on Samba, this article in particular could save you a lot of time and trouble.
Finally, this Flash video on quick-and-dirty Ubuntu-Windows file sharing with a Samba server is worth checking out. While I didn't have very high expectations for a video tutorial on this subject -- much less a video tutorial with the title, "From Zero To Samba In Six Minutes" -- I must say that I was pleasantly surprised. (As blogger Charlie Schluting points out, however, take the "six minutes" bit literally at your own risk.)