Textbox Validation On Pasting Text In. Plz Post Answer!

Hello Im using vs2005. My problem is that Im putting some validations on a form.
There is a textbox which I allow only numeric keys to be entered.I put a validation in the keypress event and it's working alright. But it's only when Im keying the character that it will validate the entries! If I have alphanumerics characters in the clipboard and paste in the textbox, my validations are violated! There are alphanumeric characters in my textbox where there should only numeric keys.

Can somebody help me out there? What I would like to do is to validate the text before it goes in the textbox. How can I do this?

Thanks in advance for your reply.

Regards.