Is there a good way to set an alert with jQuery?

i have a PDF that i need my visitors to agree to before the proceed...

So: User Clicks PDF link
 Alert Box opens: "you must agree to our statement before we give you this PDF"
 I Agree button (PDF download proceeds) / I Disagree Button (box closes and original page is displayed)

Is that the best method to handle this?

Should i use a dialog box?