You certainly don't map a drive to a network share in the same way that you would in legacy Windows networks. To be honest, drive mappings are old-school and I always steer my clients away from using them. Still drive mappings persist. In Mac OS, you'll connect to the file server a little more directly.
So far, I've found two ways to connect. One way is to access the share on the server using the URL (ie: cifs://server_name/share_name) in the "Connect to Server" window under the Go menu.
The second, (new to me since I recently upgraded from Tiger to Leopard) is a little more user-friendly. In a Finder window, all my servers and Win/Mac computers show up in the left-hand pane. I just select my server, then double-click on the share. You'll probably have to click on the Connect As button and provide your Windows server login.