Indeed, if you're using a NAS (Network Attached Storage) device, chances are you're already using Samba. Linux and Samba lies at the heart of almost this kind of hardware.
There are, however, a pair of related problems that might get in your way with Vista or Windows 7. On some of these systems, a pair of networking settings are set so that they won't work properly with Samba or, for that matter, older versions of Windows Server.
If you've set up your Samba boxes properly--e.g. you can reach your shared drives just fine from an XP box or a Mac - but you still can't see them from Windows 7, you'll need to do fixing. Go to your Windows 7 box and try going to: Control Panel - Administrative Tools - Local Security Policy Local Policies - Security Options.
Once there, set "Network security: LAN Manager authentication level" to "Send LM & NTLM responses" and the "Minimum session security for NTLM SSP" to "Disable Require 128-bit encryption." On Vista, it's a little more complicated. Here, you'll need to click "Start -> Run." Once you're at Vista's idea of a command line, type in the Run field: "secpol.msc." That will bring you to Vista’s security policy system. Once there, use "Go to: Local Policies > Security Options" and then find "Network Security: LAN Manager" authentication level. Find it? Now change the Setting from "Send NTLMv2 response only" to "Send LM & NTLM - use NTLMv2 session security if negotiated."
Once set up and running, I think you'll find Samba does an excellent job as a file/print server. For basic network services it's hard to beat. I've been using it for Windows clients from Windows 95—the horror! The horror!--to Windows 7, as well as for supplying file and print services to other Linux distributions and Macs, and it's always done the job.
From just having a server to keep your video-collection in or providing file and print services to hundreds of workstations, Samba and Linux does the job for a fraction of the cost of Windows. Give it a try in your own network, I think you'll like it.