THQ has released a demo of Relic Entertainment's Warhammer 40,000 real-time strategy title Dawn of War. Weighing in at 319.2MB (surprisingly precise, eh?), it should give you a decent impression of what's unquestionably the most interesting Warhammer videogame spin-off in ages. (Although given its competition consists of Fire Warrior that's probably not saying much.)
You can grab the demo here right now, and you should probably know that it gives you a taste of the Space Marines in a full level plucked from early on in the single-player campaign. That does mean no multiplayer action in this demo, but then you can't have everything at once, can you?
In any event, the demo also features a pair of skirmish maps to keep you going once you're through the Space Marine mission, and there's a tutorial mode so you won't get confused and wind up sobbing into your hulking space armour. They think of everything these days.