As I said in my Frodo guide, you should do "whatever lets you sleep well at night."
Personally, I don't think I'm putting anyone out on the street by downloading Commodore, Atari 2600, ST, NES, or even SNES stuff at this point. Like the Atari 2600 stuff ... I owned Pitfall on cart years ago, have obtained several more copies of it over the years (garage sales, pawn shop lots, etc), plus I know I have at least two or three other legal copies of it, one from a PC "Activision Collection" thing I bought, and the "Activision Anthology" on PS2. I've got legal copies of Pitfall coming out of my ears. Knowing that, I don't think the guys at Activision would really care that I downloaded it and stuck it on my GP32. In fact, if you could get through all the legality and paperwork, my guess is they would think it was pretty cool. Of course, maybe they would get the idea of writing a GP emulator and sell their games. Who knows.
My main reason for posting the news was to show how stupid the ISDA has become. That, and to make a minor point to all those people who say, "ROMs are legal IF you delete them within 24 hours" and "Abandonware is legal" and all those other bogus arguments that ... well, apparently. someone DOES care.
My personal "line in the sand" is, "can I buy it new?" Downloading some brand new PS2 game is wrong because you could buy it, and by downloading it, you're stealing it.
Downloading a Vic20 game (to me at least) is totally different. If I WERE going to buy a Vic20 game, I'm guessing it would either be from eBay, or from a pawn shop/thrift store. I don't think you can buy them new. Hell, I wouldn't know HOW to get a dime to the companies even if I wanted to? That's the kind of stuff I can download and not lose sleep over.