KavazovAngel: Wrong. Blizzard publishes their own games.
Wrong. They are not owned by Activision.
DelusionsBeta: Bobby Kotick is CEO of Activision-Blizzard, AFAIK. In other words, the CEO of Activision pre-merger is now the CEO of the combined company. I'd say that Zeewolf's statement is close enough.
On topic: Blizzard is a bit of a no-hoper, since they already sell Diablo 2, Starcraft and Warcraft 3 and seem satisfied with that. Sega, outside of the Total War games and the Mega Drive Classics (the latter of which are already DRM free regardless of where you buy them), doesn't have much in the way of old PC games. Bethesda kind of goes without saying, but their old PC game list basically boils down to The Elder Scrolls. THQ, on the other hand will probably be a good pick, as Relic's games and Sup Com are sliding into the "old PC games" category. I'm pretty sure they've lost the rights to STALKER, however.
Bethesda is owned by Zenimax, and Zenimax owns id and a whole slew of others. Bethesda themselves own the rights to a ton of games, like Call of Cthulhu.