Turning a old tri bike into a commuter bike

Ok, my wife has a new tri bike and wants to use her old bike for commuting 10 miles to work.  The commute will be on roads that she rides on fairly often, so I'm pretty sure the bike can handle it.  The problem is a rear rack and panniers.

The bike does not have a place to bolt the rack to the frame by the seat post.  I've seen a couple "beam" design racks that attach to the seat post, but do not attach to the rear wheel axel.  I can't imagine these racks being strong enough to carry her laptop, papers, and clothes.

Is there a solid rack out there that attaches to the frame at both points?

Thanks.