Does having a high end video card increase the overall performabnce of your rig in terms of load times and processing??
More aboutdoes card
No, unless you're running code through it, which is very unlikely becasue you would have to write such code yourself.
A video card would help unload the CPU when you're watching an HD movie though, but it doesn't have to be a high end card for that
Having a non-integrated video card does from what I understand as the CPU does a lot of the work for it(some integrated cards don't require assistance but they are rare) additionally they share memory bandwidth.
However this means that any discrete card will help, not just a high end card.