This has been asked a million times and the answer is still the same.....
A lot of people use terms like "grey area" and "touchy" to describe the legal situation. Now a few years ago I would agree with that assessment, but today this isn't the case.....
Other than starroms, there isn't a single legal method to play roms on your computer. Owning the pcb means diddly because you had to reverse engineer the hardware to extract the rom data, which violates the dmca. For those of you who are wondering "reverse engineer" doesn't need to mean decrypting the roms xor tables, ect. It just means you removed, stripped, ect data from hardware that the manufacturer didn't give you explicit access to. In other words, reverse engineering or hacking a pcb/eprom chips to remove the data. This is done to get the rom data for virtually every mame title.
And ports are just that, ports. They are technically a totally different type of software, so you have no claim there. And this is a good thing in this particular instance. It protects 3rd party console developers so that if you buy an xbox title you can't use a "backup" copy that is actually the ps2 port. This is only fair as typically diferent teams of developers are hired to port the game. If you don't buy both versions, then one team gets screwed out of their hard earned cash.
Also in both cases you aren't specifically given the right to backup, and in this day and age of stupid legal loopholes, if you aren't specifically given the right then you don't have it.
About the capcom roms collection..... If you use the emulator and software package they come with then yes, you can legally play them. Unfortunately afaik you still don't have the legal right to play them on mame due to the unique liscense agreement and the fact that the roms are saved in a proprietary format. (Again reverse engineering)
Now with that being said, about 50% of the companies that made some of the mame games are defunct and the copyrights holding the claim to the games are only a formality. So a lot of the time you are stealing from a ghost. You are still stealing....let me make that perfectly clear, but at least nobody will be around to sue you over it.
This isn't what you want to hear, I know... but asking the question again won't change the answer.
Do I think it's stupid? Heck yeah! But I still have enough insight to realize what parts of this hobby are illegal and to take that into consideration before I act.
If you have a problem with the way things are (which is more or less what I typed above) don't argue your point with me. It's a waste of time as I'm right in this particular case. Instead use that energy to write your local congressman and demand the right to make backup copies again.
But for the record, pcbs are a complicated issue because they combine hardware and software. Right now you definately don't have the right, but even if a law was passed today allowing legal backups of any software you own, you still might not have the right to backup pcb rom data specifically. But that's another story all together.
In closing..... lawyers suck..... we should really do something about that.