I have a 160GB hard drive for the OS, and 2 identical Seagate 7200 250GB drives for media. Without these drives being raided, if I was just to just throw some media on them, would LMCE be able to pick it up, etc, etc?
Sure. Shut the server down, install the two new drives, and assuming you have them set up with a compatible file system, your core will ask you if you want to use the drives after bootup.
You can say Yes, or Yes -> Use LinuxMCE File System
It's easier to let LinuxMCE utilize the drives with the LinuxMCE File system....
Now when you browse your media by Filename, you'll see two extra boxes, one for each drive.
I think, though, if your users are copying files to the core over Samba Shares, they still have to pay attention to which drive they are using. Which means, I don't believe they can just load up their main share and have LinuxMCE spread the contents around all 3 drives you'll have.
The good news is, if you sort your media by Title and use the filters, from that point of view, it makes no difference to the GUI what drive your files are stored on.
The wiki has a detailed page of info relating to how media files are organized:
http://wiki.linuxmce.org/index.php/How_are_media_files_organized%3F