Well if anyones curious I have a few 1k games, or close to it.
Top Spin 2 is a 20 hour + project, at most, and you can get 750 out of the 1000 points playing decently. Amped was fairly easy and enjoyable, managed to rack almost 800 points in less then 10 hours.
Call of Duty 3 450ish points only took me 10 or so hours of gameplay to.
R6Vegas in a few days work, and cheezly earning the multiplayer achivements can get you very close to 700 points or so.
Dynasty Warriors Empires is EXTREMELY easy to earn the 1000 points. It's just a matter of time, but my guess is you could get the 1000 in under 20 hours of gameplay.
Viva Pinata is another VERY easy to get 1000, but it does require some time investment.
Oblivion took alot of work to get the 1000 (aka time) but it was well worth it.
I've heard Condemened was pretty easy to get achivement points but I haven't look into much of it yet.
I plan on picking up King Kong down the road. It's only $12ish shipped used through Amazon, and only $19.99 new! I am also planning on getting Samuari Warriors 2: Empires, and from what I'm reading achivement wise it sounds easy as DW:Empires was, so I can recommend both of these for easy achivements.
Of course 2k6 sports games are REALLY easy to get achivement points
