If the ISO is burnt to a CD, simply insert the CD and check the name of the volume that appears on the desktop.

You can also check the label of the ISO file without burning it:

• Make sure the genisoimage package is installed (it contains the command isoinfo)
• Type isoinfo -d -i filename.iso in the terminal
• The ISO label is the value that appears next to "Volume id".

The ISO volume ID (or CD name) should contain:

• The name "Linux Mint"
• The release version
• The name of the edition (unless it's Gnome, in which case it doesn't mention it)
• The architecture (32-bit or 64-bit)

For instance: "Linux Mint 10 KDE 32-bit"