I've never played a massive-multiplayer-yadda-yadda, but I own Diablo I/II/IIX, StarCraft/SC:BroodWar, and WarCraft II-BNet and WC:III.
So, yeah, I'm gonna buy it.
I'm a big fan o' Blizzard, and I figure WOW is a good way to get into a MM-whatever. The screenshots look good so far, and I've never met a Blizzard game I didn't like.