Is there an app that forces 3rd party software to use the Aero boarders and GUI?

I belive Mozzila had a app to add XP manifests, which should do the same thing. It was on download.com

Hmm. Even if you get it, some programs might just have a reason for it.
To my PoV, forcing anything is not so good, and should be avoided... maybe you'll experience performance drops, maybe it'll not look genuine, or maybe it'll just work perfectly, as I haven't tried.

Be advised though...

Not using the standard non-client area (The window borders) is actually pretty hard, and if the app intentionally goes through hoops not to do it, there's nothing you can do about it.

If it's an MDI app, on the other hand (Lots of windows inside another window) it doesn't support Aero because MDI apps don't support Aero.