Can I install Windows 7 on more than one computer?

Just wondering what the licensing restrictions and all are. My girlfriend has a laptop that's still running on XP and I'd like to help her by upgrading it to my Win7 Ultimate x64. Just wondering if jusy using my installation disc for Win7 will cause any issues in the long term.

Also, would installing English Windows 7 on what was originally a Chinese system cause any issues? She's basically using a Chinese netbook (that's riddled with viruses and crap I'm going to clean out and advise her against downloading so much junk before knowing what exactly it is she's downloading). My system (which the Win7 came with) is an American gaming laptop.

I basically just want to redo her system. It's full of garbage. Would like to do a total restore to Win7 defaults and update all of her drivers.

Edit: Actually, I'll just make three different topics.

Really? I read this on Microsoft Answers, but wanted to come here to verify.

For the lazy (or can't access the site/you're reading this in the future and the question has been taken down):

Question : "I love this OS and would like to install on all of my computers (many).
Can I use same serial number for ultiple computers?"

Answer (from a "Support Engineer" ranked member): "Hello owonhee,
Thank you for using Microsoft Answers forum. Your product key will work for up to three separate computers, so if you want to install the the RC on another PC, you can re-use the same key."

By what I'm understanding from MS Answers, I can install up to three copies if I have the full software. Users that got their OS via Upgrade are only licensed for one.

TL;DR : I'm getting conflicting answers.

Well crap. That includes Ultimate?

What happens if you install it on another computer anyway? It'll refuse to update or something?

Surely it won't refuse to install altogether. It wouldn't make much sense because what if someone removed Windows from their system and then reinstalled? Also, how would anyone install Windows without being connected to a network?

Basically, what are the consequences of going through with this?

What happens if I shutdown my system and install it on her's though? It won't allow updates or what?

Haha, getting legit Windows in China is a chore. There's close to no legit software here, unfortunately. Most software are pirated copies. That includes movies and games.

Legit game consoles aren't even officially sold in China due to piracy (and political reasons). So, they just import consoles from Japan (sometimes Hong Kong) and mod them to run copy games.

I have no idea how they run all these pirated versions of Windows then. I think it just disables their updates. I might try some tricks but one thing is for sure - I won't use my own serial key.

I think it can be installed, but these forums don't want to be associated with illegal stuff so a straight answer on that won't be given. That's cool.

Yeah, just about everything can be copied here. Even the alcohol in the bars is often knock-off crap and you actually have to look for legit kinds.

Their websites are all lame knock-offs of foreign websites as well. They just create something similar and then the government blocks the foreign competition (because they don't want websites beyond their control being popular among Chinese people, and they want only their own economy to profit from anything).

The sad thing is that I really want to support software developers but it's really difficult given where I'm currently living blah.

I love China, but software and gaming here is crappy. Unless you prioritize cheapness over quality, then it's awesome. I have a book full of knockoff Blu-Rays, though now I get Cinavia copyright problems when running them on modern American Blu-Ray software.

It's much cheaper to live here financially speaking, but there's definitely things I miss. One of those things are good internet and legitimacy of products.