Here's what I bought from Summit Racing awhile back:

Husky Liners: http://www.summitracing.com/parts/HUS-30612/

I've had them for about a year now, and I love 'em. I doubt you can beat Summit's prices either. The link is to the front set, in gray. You'll have to search for the rear set, and/or other colors for your XK. The rear covers the entire floor, up and over the hump.

They fit like trays, and like this last week-on-the-Oregon-coast trip we just got back from, sand and dirt is completely contained. You just pull out the mat and dump it. The tray-like design also catches water. There was tons of sand as we drove on miles of beach.