Windows 7: Upgrade 32bit to 64bit with same product key

Hi i wonder is this possible. I'm now using Win7 Home Premium 32bit and i have 4 gb ram but i cant use it because my os is 32bit. I want to upgrade it to Win7 Home Premium 64bit with same product key. Can i do this?

Sorry for my bad English.

You will need to do a clean install, but yes, you can use the same key..

If i won't format drive "c" and install windows again to drive "c" will be there any problem?

None at all.. you will find a windows.old file in the c:/ directory that you can safely delete and you will be good to go...

It means my files, programs and settings will stay in computer and i can use my computer like the old system but 64 bit?
I want to be very sure because there are my very important files in harddisk.

No, you cant do an in place upgrade from a 32bit OS to a 64bit OS..You must do a clean install. Be sure to backup your important files and documents before you install...

Ok. Thank you Tews

Hi it's me again i downloaded a windows 7 ultimate x64 dvd in English. Now i saw something about windows reactivation nubmer i have 2 remaining reactivation. Does that mean if i install windows 7 home premium from ultimate dvd there will be 1 more reactivation? And my windows 7 is Turkish now. Will be there any problem in activation?

If you have a problem using online activation use the phone method and you will get it activated.

With this method i can reinstall windows more than 3 times?