SELECT Count( * ) AS UserPosts, POST_POSTER_NAME
FROM ubbt_POSTS
WHERE POST_POSTED_TIME > UNIX_TIMESTAMP( '2008-04-20 00:00:00' ) -86400 *60
GROUP BY POST_POSTER_NAME
ORDER BY UserPosts DESC
change 2008-4-20 to whatever date you would want the 60 days to be counted back from..
*note* this is off top of my head.. i did try it to see if it passed mysql parser at least..
ps: this is a little diff than waht you asked for -- if you just want it simple (like you posted), i'll give that a whirl
