There is a problem with upgrading Windows 32 bit to 64 bit by installing it twice. If you are using it for any wordprocessing applications including Word, Powerpoint, Access and Excel, the alphabet generator in the computer gets overloaded because two operating systems are demanding double the number of lettering to stick on to the inside of your monitor screen.
Recent tests have shown that even with moderate use, a successfully hacked 64 bit installation done by joining two 32bit installations together results in the letter "e" running out. You either have to wait about 90 seconds for more "e" letters to be manufactured by the alphabet generator or alternatively, save a whole page of "e" letters on a USB stick and copy and paste them into your document as you need them. In extreme instances, it's been reported that the letter "t" can also be depleted by using this hack. It has even been reported in some forums that the alphabet generator has overheated and has burnt out or has caused other damage to the insides of the PC. As all us PC experts know, alphabet generators are difficult to find. There is also the thorny issue of the internal monitor wipers. These are wipers that are fitted inside your monitor, that are used when you hit the backspace key to remove the letters that have been stuck on. They too can end up being overladed if you join up two 32 bit systems and they are expensive to replace as it requires specialist heavy duty hammers to fix them with.
So, fwitt, my suggestion is to stay with 32 bit, unless you are using your pc for heavy graphics / video processing, you won't need the extra kick from 64 bit and you will be safe in the knowledge that the alphabet generator will be working reliably as well as the internal lettering wipers in your screen.