Out with the Old, in with the New!

8/21/2007 12:42 PM PDT BY TMZ STAFF
The countdown is over! The day has finally come! Gentlemen, start your engines ...
Hayden Panettiere, Kim Cattrall
Hold it, boys! Hayden Panettiere isn't the only birthday girl today. "Sex in the City" vixen Kim Cattrall turns a spry 51.

So the question is ...