This windows copy is not genuine how to solve?

I found that many of my classmates are equipped with win7, but most of them are pirated. After using it for a while, it will be "black screen", in the following Such subtitles appear: this windows copy is not genuine. So the personalization of win7 is in vain?
Is there no way?
The answer is yes.
The official default activation method:
Said to be "official" "default" "activate" & rdquo; method is correct, because this method does not really activate our windows7, but let us trial time extend. Specific action: Open the attachment —– command prompt. (Note that you want to run using the right-click admin mode). Enter the command of “slmgr.vbs/rearm” on the command line to extend the usage period by 30 days. After restarting the system, it will be restored to 30 days.
Please note! Be sure to wait until the prompt appears and restart the system.
Enhanced operation:
After the above method 3 times, after a total of 120 days, it will not be used again after this time. To proceed to the next step, modify a key in the registry, you can reuse the above command, please open the Registry Editor (how to open the registry), and then navigate to "HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsNTCurrentVersionSoftwareProtectionPlatform”. Locate “SkipRearm” in the right pane and change its key value to “1”, you can use the “slmgr.vbs /rearm” command again, this key value can be modified a total of 8 times, that is Say we can reuse the command of "slmgr.vbs/rearm" for 8 times.
So the time you can use for free is: 30 days for the first installation, plus the first 3 times 90 days for slmgr, and then modify the registry for 240 days. Win7 can be "free" for 360 days! ! (It is said that this method will be available when VISTA is just out)