Windows vista
 

I have just built my daughter a PC and I was going to install windows Vista Ultimate on it. I have 2 copies one is already running on my pc, can I use my serial number to install vista on her PC as it will be at the same isp when it goes on line?? I could use the 2nd copy but it seems a waste of cash to use it if her PC if it will work properly and still update ??

When you try and activate it is will say it already is activated, so the answer really is no

It doesnt go on the internet connection the key (or serial number generated for activation) goes on the hardware in the PC, change your hardware too much or too many times and you will have to reactivate again, and then that usually means a phone call to Microsoft

Now you can use the same key, and phone MS to say you have had to reinstall it, but Vista continously checks the key and activation status, but doing that would technically be illegal

I will put her serial in as I can't be bothered with any hassle, thanks :)