I'm posting this in case it's helpful to those who (like me) have some Windows knowledge but little Linux skills and who want to use UCS as a simple file server on a Windows network (workgroup). If you want to save a few bucks on a Windows server license then UCS is an excellent choice. If you're having trouble accessing your UCS server from a Windows PC, and terms like "samba" leave you feeling a little confused, then read on...
Setting up UCS as a simple file server on a Windows network:
Install the application "Active Directory-compatible Domain Controller", either during the initial UCS setup or afterwards from within the Software section of the web admin interface.
Create a share in Domain > Shares. Set the "Directory owner group of the share's root directory" to "Authenticated Users". Tick the Group/Write checkbox in "Permissions for the share's root directory" (assuming you want users to be able to write files and not just read them).
If you haven't already, create user account(s). Take note of the user names and passwords, because Windows Explorer is going to prompt you for them (see below).
At this point you should be able to browse your shares from Windows by entering in \your UCS server's IP address into Windows Explorer. You'll be prompted for a user name and password - enter in the appropriate details from step 3 above.
You probably want to also access your shares in Explorer by entering \your UCS server's computer name also. To do this you'll need to know the name of your server as Windows sees it from your network. To find this out, open a command prompt on your Windows machine and enter the following:
nbtstat -A [your UCS server's IP address]
e.g. nbtstat -A 192.168.1.11 (note the "-A" parameter must be a CAPITAL A)
You should see a table of name information appear, with headings "Name", "Type" and "Status". The first entry should be the name of your UCS server as seen by Windows. You should be able to enter \[UCS server name as reported by nbtstat] into Explorer to browse your UCS server's shares.
I hope this helps others who are familiar with Windows but not so much with Linux. If anyone with better skills than I wants to correct anything I've missed, or knows a better way to set up UCS as a simple file server for a windows network, then feel free to add to this.