ok i have a ps3 but i have a questions about 360

who makes achievement points for xbox...

microsoft or game developers??

k thanks 

Its the Game developers that add them to the games.

so then they will start adding em to the ps3 when home comes out then?

I hope so!

Does microsoft do any sort of quality control though?
I remember that avatar game where you can get 1000ms points in merely a few seconds with no trouble at all.

 yeah i think that just proves game developers make em cuz microsoft would not make a game whre u get 1000 points in literly 3 minutes

game devs. and yes devs will be putting achievements into home.

but i hope they realize that the number for your achievement is important. i dont want to be getting points worth like 150 beecause then i would have a gamerscore (if i can use that to refer to ps3 achievements) would be like 200 000

Games are fixed at 1000 points on retail games, 250 can be added with DLC though, and XBLA games are 200. How the points are given is down to the dev, so it varies as to how difficult they are. As you have already mentiond Avatar is stupidly easy to get a max score, whereas some games are really hard to finish. IE: GRAW required you to climb to the top of the world leaderboard for an achievement and Gears of War's 'Seriously' needs 10000 kills in versus ranked matches.