Quoting Coelocanth, reply 1Note there are regional restrictions and pricing, but still some good deals there. I'm mostly into RPGs, so I'm looking forward to seeing what pops up in a couple weeks, although I'm tempted by Civ 4.
Do you use the same name on GOG, perhaps?
As a matter of fact... yes. 
Anyway, back on topic: D2D used to put some really annoying DRM on all games sold (unless marked as DRM-free on the product page). I am not sure if they have made their activation experience less frustrating.
I haven't used them for long and only use them for cheap games I don't care all that much about, but yes, unless it's specifically marked DRM free, they still use an activation system. I wouldn't say it's 'really' annoying, as it's simply a matter of entering a game key and activating on-line, and that's it. I don't like it, but as I said, I don't buy anything I really really care about from them.