A half-decent DVD player (mine's a Sony) should allow the VCR to hook up to it, and the DVD then plugs directly to the TV. My cable box also plugs into the DVD, which simplifies everything.

If I put a disc into the DVD it automatically plays into the TV without any mucking about, and the DVD remote even controls the TV.

My DVD also takes over switching of the VCR and cable boxes, and even simulates surround sound (it has Dolby 5.1) for signals that aren't encoded. I can even record from cable whilst watching a DVD.

Playing your DVD through your VCR shouldn't degrade the signal if you are using SCART, but I definitely wouldn't recommend inserting an RF modulator - that really is defeating the object!!

You can get simple non-electronic SCART switch boxes very cheaply that get around problems of not having enough SCART sockets to go round, or more expensive electronic ones with remote controls.

The moral? Buy a machine to do what you want instead of settling for what some manufacturers say you should want!