Password validation in ASP.NET - Please help

Hi all,

I need to write some patterns in ValidationExpression that match to a rule
for the password validation while using the regularExpressionValidator.
Here is the rule for the password:
1- Minimum of 8 characters.
2- Containing at least 1 alpha uppercase, 1 alpha lowercase, 1 numeric
and one special character (e.g: #,*,@..) .
This is a general rule for the password.

I'm not smart guy to write this ValidationExpression correctly. Please help
me to do that.

Thanks in advance.