vBulletin Password encryption schema

[Ph0eniX]

Can anyone tell me what it is?
I basically have a custom application written in ASP.NET that uses the vBulletin database to authenticate users. It doesn't work since I upgraded to vBulletin 3.xx a week ago. The SQL statement that that worked fine with vBulletin2.xx goes like this:

SELECT username,password from user where username  ='" & txtUser.Text & "' and password = md5('" & txtPassword.Text"

I don't know PHP so it's a nightmare for me trying to figure it out from login.php. I thought it would simply be "MD5(password_column+salt)" but when I input that into a query and run it, it generates a different hash than what's in the password field. Please help!

TIA