best way to remove window trim and not wreck paint?

i was using a screwdriver, but i stopped because i felt like i would be ruining things....where can i get that tool in the picture?

should be able to get it or something like it at a local body shop supply store:

http://www.yearone.com/serverfiles/fbshopmain2.asp?cat=1

$15 bucks doesnt seem bad:

http://www.yearone.com/serverfiles/fbshopmain2.asp?cat=1