Best way to upload a file and send as attachment.

What is the best way to attach a file to an email. I have an HTML email form which I have a reply to: field, a message body, a field to attach a file (with a browse button), and a send button. My first question is how to set up the browse button to open a common dialog box so the user can select a file? My next question is how would you set up the mime funcitons in PHP to attache either a word document or a pdf document? Thanks! /T