I have Macs which include most languages on the initial install and you can switch languages in about 10 seconds without having to reboot. Also, you can install Windows on the Mac and run it as a Windows machine if need be. (Can't do the reverse on a Windows machine.) Now, on a Mac right out of the box, you can install Windows on a separate partition and you just boot into whichever system you want. When you want to switch back, you need to reboot. There are two programs out there which allow you to switch between Windows and Mac on the fly and have both running on your machine simultaneously. I use one of the programs-called Paralells. I'm not telling you all this Mac stuff to sell you on a Mac, but in a roundabout way to answer your question.
As I said, I use Parallels so I can switch over to Windows the very few times I must use Windows. The main case is when I do Internet banking or buy something online because my bank, ICBC, requires Windows ActiveX and Internet Explorer - which I despise but am required to use by the bank. (The other time I may need it is I have a lot of old files in MS Works formats as I used that from about 1995-2004 on my Windows' machines. Too many files to do a batch convert. So on the occasions I need some file, I have to switch to Windows, fire up an old version of MS Works and convert/save the file to an MS Office format (doc, xls) which Mac can read.
So (to get to your question) when Windows 7 came out followed shortly thereafter by the next version of Mac OSX, I decided to upgrade to the latest Parallels. Too, I had been using a pirated version of Windows XP on the Windows partition so I decided I'd try to buy a legit, English version of Windows 7. Windows 7 had about 6 or 7 flavors rising in cost from pretty cheap to severely expensive. I spent a couple hours in Sanlitun in the Apple Store and then another software store an Apple Genius directed me to in search of the cheapest English version of Windows 7 I could find. I could only find the most expensive version available in English - Windows 7 Ultimate or something like that and it was going for about 2000 RMB. The guy at the store (not the AppleStore) told me he was pretty sure I could buy a cheaper version, like Windows 7 Home and then add the language pack for English. But I've learned that "pretty sure" especially coming from a Chinese tech guy, is usually a bad harbinger. So I left the store without buying anything and went to a cafe to research the issue online. After some extensive googling, I found that (1) Only the two most expensive versions of Windows 7, Enterprise and Ultimate allow switching of a Chinese version of Windows 7 to English. The lower-priced versions don't, and (2) Microsoft made a conscious decision not to release any English version of Windows 7 in China other than Ultimate. So either way I was screwed.
In short to answer your question, in China you're gonna need to pony up a lot of RMB to Microsoft for Windows 7 Ultimate if you want to be able to use English.
What I did. First I went to an electronics market and found pirated versions of Windows 7 Ultimate for 10 RMB. But I could not get it to install on my Parallels partition for whatever reason. (Could have been the key had already been discovered and blocked by Microsoft.)
I also discovered I could no longer install my old pirated version of XP, not that I wanted to anyway.
In the end, I didn't use Windows for awhile. Then one day, Microsoft made available for free a beta version of Windows 8 so I downloaded and installed that flawlessly. Very weird and different interface from Windows previous versions, but it worked. Then recently Microsoft made the beta semi-official by issuing a "Windows 8 Consumer Preview" which fixed most of the beta issues. I'm now running that on Parallels when I need to use Windows and it's been flawless. I don't know how long it will last as at some point Microsoft is going to release the final version and charge for it.