It looks like you can only change one of 2 things which is the TV used or the video output of your Mega Drive to get rid of the bad pixel visuals.
Consider getting a SD-TV for your Dad's pad, or more specifically a high end model with a quality tube. With flat screens all the rage most people are getting rid of them for low prices or free which is what I paid for the 32" Trinitron I use for my older consoles. This gets you out of the more expensive options everybody has already mentioned.
Regardless of display used higher quality video output is always good since it cuts down on the picture noise. If you have the Model 1 Mega Drive they have RGB SCART cables that will clean up the picture quite a bit. Here in the west we can patch SCART to work on our TVs but its way more expensive to get it to do RGB output that popular mods settle for S-video and Component outputs instead. So if you have native SCART for heavens sake use it.
Still I should ask what does the output look like on your Mega Drive, how many pins on the DIN end? Over here our Model 2 Genesis removed the superior DIN connector that offered C64/others monitor support. More noise and rainbow bands in the second revision I'm afraid.
Upscalers are quite good from what I've seen and the SLG 3000 looks interesting but I'm still on the fence about scanlines inherent value, technically its authentic but I quite like seeing the pixels au naturel.
Well that's all I can say, hope it helps.
