Unfortunately, Real were peeved, they went to the EU Commission, and they found that bundling software was anti-competitive and very illegal.
This case matters in the US, using US laws. (right now)
Microsoft thought that and it made Bill Gates cry.
Microsoft tried some shady things to become very dominant in the PC world. It wasn't that they tried to say who could sell Windows, they tried to stop PC makers from selling anything else, along with other things.
They're just using open source software to run it properly.
They don't modify Leopard as far as I've understood.
It is preinstalled, works fine, and even updates fine. All software does work, as you will be able to see on the Psystar forums.
I've read the Psystar site, and the part about how after the 10.5.3 update you get from them, the Apple Software Update now looks to Psystar's servers, and you should not try to install the updates from Apple is kinda fishy. I have no proof, since I'm not going to decompile everything (not even sure how) and check, but it seems like they have made some changes to Apple's software. They also say that only the Leopard restore disc will work, not the retail one. Again, sounds like something is different.
Again, whether they actually modified Apple's code or not will be proven in court.
They didn't need to ask because apple's EULA violates a lot of laws.
Except Psystar is not an end user, they are an unauthorized reseller. BTW, which laws? Since this is two US companies going at it in the US, over US laws, only US laws can apply.
A EULA is not a law, it's a usage restriction. If a EULA is held as illegal, you can choose to ignore it. That's what Psystar have done.
Anyhow, they can overcome that EULA by just sticking an apple sticker on their boxes saying "Not a product of apple" next to it. It'd technically be an apple labeled machine then. Technically.
Actually, it's been held that EULAs are legally binding.
Links:
ProCD v. Zeidenberg
EDIT: Removed second link because the wikipedia link to the actual decision was broken.