Personally, if you've a genuine copy, I'd only install that key on one machine, and use a BIOS mod or a loader on the other. No point risking a genuine key, as once all is said and done, they're both going to appear as genuine regardless. If the fake gets busted by a future update, your genuine machine will be untouched.
I've installed the Win7 Ultimate Signature Series I received from the launch party on 5 machines, I have not had a problem. You dial the phone number, listen to the automated prompts and get validation. Don't hack your BIOS if you don't have to.
Like someone said, just use loader on second computer. If MS wacks it, then you can uninstall loader and set trial back to 30 days like 3-4 times. The dev's here are obviously very gifted and always on it when it comes to keeping ahead of the game! People do sell legit keys on the internet but I don't know where exactly?
Question, regarding updates, are these leacked update packeges desinged to provide us with impoved codes but without any MS anti-loader activation cancelers. I ask cause i just update as usual and daz loader has worked fine sofar? My bad if I'm off topic?