32 bit to 64 bit

Even if you do find all your drivers, going to 64 bit from 32 bit requires a complete clean install. You can not upgrade. That means all data and programs will need to be saved and re-installed. I doubt you would gain any use improvement by doing the change on your system.
 
Check your system information in the system properties panel, but IIRC that model has a Pentium D 3GHz, which is 64 bit capable. It originally came with Vista, but IDN if there are Vista 64 bit drivers available.

The maximum memory is 4GB, but be sure to buy any memory from a site that will guarantee compatibility as not all will necessarily work.
 


You technically can, however drivers may become an issue, and it would require a complete new install to be done, as there is no direct in-place way to upgrade a 32 bit OS to a 64 bit OS, the OS kernel is different.

There is no good reason in this case, nothing to be gained by going 64 bit on this particular PC. The main single biggest advantage to installing a 64 bit OS is that you can install and make use of more than 4gig of memory. Your PC only allows 4gig of memory max. Win XP 64 bit is not advisable, as it was never widely adopted, drivers are very limited, and all support has ended.

But besides the 64bit part, there are many reasons to dump XP and start using a more modern OS, like Win 7 or Win 8. Honestly, the only good reason to hold onto XP any longer is if your hardware is so old and outdated, it simply won't run the newer software. If this is the case, its really time to start thinking about a new PC.


 
It is possible, I've installed to older machines than that, but what is your goal in changing away from XP? Is XP having issues?

If you stay with 32 bit Windows 7 for example, the Vista drivers or some XP drivers installed in compatibility mode may work, but I really would not advise it unless there is a compelling reason to leave XP.

 
If it has been used for a long time, XP is often much faster after a clean install or at least cleaning up extraneous applications and junk registry entries.

I would run the free version of Glary Utilities from HERE and see if you can speed it up. Also, uninstall any programs that have been accidentally installed with updaters and turn off any services or startup programs that are not needed.
 
Win 7 won't speed an aging computer. In fact, it may end up slowing it down. Drivers may not be available for some devices. A clean install of XP would be the best for you at this point, I agree. If the old machine is starting to feel like its simply not up to par anymore, well, I already told you what needs to be done!
 
Afresh XP install and the system will run about like it did out of the box. However MS has stopped supporting XP. This means that even after you fully update it, your system will be increasingly vulnerable to security issues. So "let the user beware" and stay away from questionable web sites, bootleg software and similar things. You could install Win7 and adjust the performance features to make it almost like XP. Given the age of your hardware there is not much you can do to make it faster. My suggestion is to use Win7, shut off areo, the system sounds and other bells and whistles. You will have an OS that is much more secure. Try to start putting away a few coins each day and soon enough you may be able to get a more capable pre-owned replacement.