Updating # of posts?

[tubedogg]

Ok this is gonna sound kinda weird but here goes...
I'm gonna run a contest similar to that of ascifi.com and dvdcouponpost.com where the winner is determined by x # of posts in a certain amount of time. I would like for my users to keep their current # of posts, but also have a total they've made for the contest (i.e. from starting at 0 at the beginning of the contest). I'm just gonna use the biography profile field, but here's where my question comes in: I think I found on the reply PHP page where I would need to insert code to increment a number stored in that field. I believe it's right after this in newreply.php:
// update user stuff

// some other code here

$DB_site->query("UPDATE user SET
".iif ($foruminfo[countposts],"posts=posts+1,","")."
$dotitle"."lastpost='".time()."' WHERE userid='$bbuserinfo[userid]'");
Is that right? And could anyone give me a little help with how to do the actual incrementing? I think it's something like
$DB_site->query("UPDATE userfield SET field1=field1+1 WHERE userid='$bbuserinfo[userid]'");
Would this be right? Thanks for any help you could give me. :)
One other small question: What's the difference in newreply.php between postreply and newreply?

newreply is the code that shows the page that you enter the post into. postreply is the code that processes your post and submits it to the database.

*bump*

Anyone, please?? :D

*bump*

Thought of something else. Would it be easier to just create a custom profile field instead of using one of the existing ones (i.e. Biography)?

Thanks for any help. :D