We've been hacked and I don't know the first thing about it

[terracore]

Here is the link to my site:

www.AvianNation.com

And it's been hacked. Any suggestions on how to fix this? I'm afraid to log into my admin panel as I have to enter my password and I don't know who's password that they might have. Obviously it is one of the admins. Right?

This sucks, so any help would be good.

New info:

The site was hacked by ALQAISER and the hack "theme" was some sort of pro-muslim thing complete with graphics and music and some kind of warning.

I'm not sure who they are or their motivation (it's a forum about parrots, hardly controversial). I also don't know how the hack occured. The database seemed untouched. I really know nothing about computers or coding. I was already running the latest version of VB (3.7.3 patch 1) and wasn't sure what to do to fix this problem or get the board running again so I went through the motions like I was upgrading it (even though its already the latest version) and thankfully that seemed to restore everything to normal. Since I don't know the vulnerability that caused this, and may still exist, I did the common sense things like changing passwords, etc. I also deactivated the following mods:

CYB- CHATBOX
CYB- PAYPAL DONATE
CYB- AUTO BIRTHDAY GREETER
WHO HAS VISITED TODAY
PASSIVE VID

If anybody can look at the board aviannation.com and see if there is anything I can do to close a vulnerability let me know. Also if they think one of those mods had anything to do with it? Can I reactivate them?