Web Browser Compatability

When doing a website, do you think it's right to be code for only certain browser (ie the most used browsers like Firefox & IE (latest ver)) and to just say to other users of browsers like Safari, IE 5 , "sorry you cant use this site"

If you had to pick, choose opera when testing your webpages. it's the most compliant browser out there.
konqueror

>>12,13,15,16
w3m