yes i was.

The COUNT(*) method of doing the query is rather intensive for your server if you have it in phpinclude_start - it's a slow query (the more posts and threads, the slower) that can really hog down a server. I'm interested in seeing NTLDR's method though...

How many queries does this use? It is too hard on the server?

2 queries, and no, the queries aren't really that much of a strain on the server :)

How would you do it? ;)

Haven't looked into it much, but apparently NTLDR has a working method :)

NTLDR, buddy, can you share it with us? ;)

For those arguing over this, it's quite simple. If you installed the version that counts old threads with new posts as new threads, then those threads aren't neccessarily new. Therefore, "There have been {2} posts in {1} threads since your last visit!", because the number of "new threads" is really the number of threads with new posts in them. If you installed the version that only lists threads started since the last visit, then the original phrase is more correct.
Not installing this 'cause of the permissions thing. Gonna take some time and look into it myself.

I've found a problem with this, if I go to new posts, there's 8 new let's say, New Posts shows all 8. But, when I view all of the 8 posts, the hack still shows that they are new. Shouldn't the hack show 5 new threads if I've read 3 of the 8?

Can this be fixed?

Nope, that's how vBulletin works. Click on 'marks forum read' or wait until you expire (time limit depends on what you set in your Who's Online options) then check back on the forums :)