Update instructions here
here.
Official isos
here.
LMDE is linux mint, but based upon debian instead of a crappy ubuntu base (the result typically is superior stability). LMDE is also a rolling release (in this case, a semi rolling release, they release update packs).
They set it up so you can keep your gnome 2 desktop if you are going the update route. If not sticking with gnome 2, go ahead and update and you'll get the fork of gnome 2 which is called MATE which works great in my opinion.
If not updating, they have fresh new isos with update pack 4 included that come in xfce and MATE/Cinnamon 32 and 64 bit versions of each.
Thoughts on cinnamon...
Cinnamon is pointless as all hell and runs slow. I don't see the point of cinnamon with it essentially trying to replicate the MATE desktop environment with the bird **** glue and underpinnings called gnome 3. Why is 3d acceleration a requirement for a 2d desktop? Who the **** knows, and you can't turn it off (thanks gnome 3, that would fix the speed problem on a netbook).
Cinnamon is still a work in progress, gnome 3 which is a non task oriented desktop that can be made into a task oriented desktop. I say how much lipstick can we put on that pig?