It really doesn't take much to crack a windshield. BTDT, and I was extra
careful. Off the cuff, I'd say you have a 50% (completely unsubstantiated
figure!) chance of cracking your windshield, less if you've done (cracked)
one before. I suggest you check the rates of professional installers and
then decide if you'd rather take the risk.

-- 
Sami ('75 Westf.)
dakhlia@wuecona.wustl.edu
http://wuecon.wustl.edu/~samid/