Now if you want to know the difference in 32 bit and 64 bit I would simply refer you to Wikipedia however this FAQ on MS site will also help you
In simple language a 32 bit operating system can support memory upto 4 GB however a 64 bit OS can support more than that. The more memory you have in your computer the faster would be the processing time by the CPU. Now if you got 64 bit operating system installed it simply means even if you are working on different applications like editing a video,listening music,download and installation of a software is going on your computer would perform well provided you have the better CPU,good RAM with a 64 bit OS installed.
Now lets see how we can check if the processor inside the computer is capable of running 64 bit OS.
1 ) If you bought a branded system and know the model number simply go to manufacturer`s site and see if the drivers are available for 64 bit OS then your processor can run the 64 bit OS lolz but scenario can be different the drivers would be for your motherboard and other hardware so if you have a motherboard of same model number and anyhow you changed the processor sometime which cant run 64 bit OS then it wont work for you. Do I make sense? No, let me give you an example here I got a HP desktop whose motherboard went bad, I got it repaired and again it went bad after 20 days so I just threw it at my store and bought a new mobo. After sometime I saw in my store that I have many things in spare to build another PC apart from motherboard and CPU. Anyhow I came to know about a reliable shop for mobo repairing so I just went and got my motherboard repaired and bought a second hand CPU from the shop to build the alternate test PC, hope now the scenario is clear.
2 ) Windows Vista and Windows 7 users can check by following the steps below
a ) Open your Windows properties either by making a right click on computer then clicking on properties or you can simply press the Windows key ( the key on bottom left with four blocks printed on it ) with the Pause/Break key on top right hand side of your keyboard then click on " Performance Information and Tools " on the new window at the bottom left as shown in image below
b ) Now on the next screen if you see the message " Your Windows Experience index has not yet been established " click on Rate this computer as shown below
c ) It will take some time in rating your computer then a screen would appear with your ratings as shown below,you need to click on " View and print detailed performance and system information " option
d ) Now you will see the detailed info about your computer and whether if its 64 bit capable or not. See in the image below once I performed the above steps even if I am running a P 4 processor ( image shows the number of core processors ) its capable of running a 64 bit OS.
3 ) Now if the above steps are too much for you then the third option is to simply use a wonderful software known as 64bit Checker.You only have to simply double click the software on the computer that you would like to check and it will show if it supports 64 bit OS or not
It will tell you the type of OS currently installed on your computer and whether it can run a 64 bit OS or not. So start checking your CPU for the capability and do share your experience with us.