Just got Toshiba D-R410 DVR with upconversion. Does this have to be hooked to TV via HDMI cable to get upconversion or will component (RGB) work? I have a Panasonic 42" HD plasma TV. Are there any special settings on player or TV or does it do upconversion automatically? What if I only have 1 HDMI input on TV that is already being used by satellite box?

I would bet that it's upconversion is for HDMI only There are usually settings on the DVR for determining what signal is output. You may want to try some combinations of settings writing down some sort of evaluation of each and pick what looks best.

Your TV will always deinterlace and scale as needed to match it's native resolution. So you already have "upconversion" (more correctly called upscaling.) The question is whether some settings on the DVR can improve over what your TV already does.