I have a 05 Ford Five Hundred Limited and am looking to upgrade my speakers...Any suggestions?

Are you looking to add an amplifier to your system as well? If not you may not notice a huge difference in sound.

Get some components and push em with a nice amp.

Isn't that thing equipped with 6X8's all around? If so, that kinda sucks. If I were you, I'd put some standard 6X8's in the rear, and buy an adapter plate for the front speaker openings and put a set of 5.5" component speakers in there, with a small amp on them, of course.