Legality of Roms

Basic Questions:
1. Is it legal to download roms if you own the original cartrige?
2. Is it legal to download roms if you own the original cartrige, but not the hardware to play it on? (ex: You own a "Paperboy" cartrige, but have sold your gameboy and no longer have it.)
3. What is up with the 24 Hour thing? Is it real? (You may only keep rom for 24 hours if you dont own the cart.)
Just wanted to know what you guys know/think, because I have seen so many different idea's and I dont know what is true or not. It would be nice to play some GB games on my PPC, but I dont want to do it illegally. I do own "Paperboy" and "Billy Bob's Hunting and Fishing", but I want to know if I can legally download the roms for them?
1. Is it legal to download roms if you own the original cartrige?
2. Is it legal to download roms if you own the original cartrige, but not the hardware to play it on? (ex: You own a "Paperboy" cartrige, but have sold your gameboy and no longer have it.)
3. What is up with the 24 Hour thing? Is it real? (You may only keep rom for 24 hours if you dont own the cart.)
Just wanted to know what you guys know/think, because I have seen so many different idea's and I dont know what is true or not. It would be nice to play some GB games on my PPC, but I dont want to do it illegally. I do own "Paperboy" and "Billy Bob's Hunting and Fishing", but I want to know if I can legally download the roms for them?