I am getting a new laptop which will be eligible for a free windows 7 home premium upgrade.

I also have windows xp on my desktop, will I be able to use the same serial number on my laptop and desktop?

Also, I have read that windows 7 uses less memory, etc and is faster just like xp.

how can i make my computer automatically run windows xp rather than it giving me a choice of xp home 1st or xp professional 2nd. Yes i have a dual operating system. I deleted one but it still asks me to make a choice.

I have installed Windows 7 Home Premium in my computer and activated it.What happens if someone stole my key.Can the thief activate windows 7 home premium on a different computer using the key which i am using already without contacting Microsoft?Can i activate windows if i reinstall using the same key after this?
@kingkrunal
thanks for the advice but i dont need serial keys as i have the genuine one.I asked this question because i was afraid if someone stole my key.

At the moment i use our family computer (its an XP) and have recently been looking into buying myself a laptop. I have just stumbled across windows 7 and it looks very similar to vista…. I wondered if anyone has tried it or knows lots about it? I was thinking maybe windows Vista laptops will be reduced when the Windows 7 software comes out but if its alot better maybe I would be better of buying a new one.
Any tips/information welcome