If your computer processor was designed to carry one type of operating system, then your upgrades and drivers must be associated solely with that version of the operating system. For example, if you use a 32-bit processor, you can only use a 32-bit operating system, 32-bit drivers, etc.
Some of the concerns are whether or not programs designed to run on 32-bit machines will work on 64-bit machines. Fortunately, 64-bit Windows is capable of running 32-bit applications, operating systems, along with driver support. If unsure whether or not 32-bit hardware or software will run on a 64-bit operating system, the best way to find out is during installation if you already happen to have that piece of hardware or program. If there are any error messages that you receive, 64-bit Windows won’t be able to run it. Alternatively, you should only really search for 32-bit applications if 64-bit ones are unavailable.
One thing to keep in mind is while there are 64-bit versions of web browsers available, some plug-ins are not available. So if you like going on YouTube, or other websites that require Flash, it won't run. Attempting to install Flash on a 64-bit web browser, like Internet Explorer, will turn up with an error message. While it's a slight annoyance, it won't heavily effect your internet experience, as 32-bit browsers such as Internet Explorer, Safari, Firefox, Chrome and Opera all function under 64-bit Windows 7.