well, there are no good “legal” roms…
most roms now are so old that they are almost classed as abandon-ware, so your probably be ok, it all depends on your countries copyright laws, but anything before nes/master system and upto PSX, you will find very unlikely that anyone will try and prosecute you for having them..
I am not telling you to go and do it, but im just saying, its your choice, but your pretty safe..