...With 8GB or more of RAM there is basically enough space in which to store all the data the operating system needs, whereas with 4GB or less you often experience performance ‘blips’ or stutters that occur as a result of the system accessing data in the paging file on the storage drive.
The best way to experience how adding memory improves the responsiveness/feel of the computer is to actually use 8GB or more of memory for a few weeks, and then drop back to 4GB. As Joni Mitchell famously said (though probably not in relation to DDR memory), “you don’t know what you’ve got ‘till its gone.” and this is very true of more RAM. With 8GB or more you simply get used to the smoothness and responsiveness of the system, and the ability to leave all your applications running. The latter aspect is where Windows 7 really helps because, as mentioned earlier, the interface intelligently manages the different windows and applications, making it easy to navigate."
Windows 32-bit versions are a good choice for the average user with older hardware and/or software, or someone who only uses one or two windows at a time. Those who consistently bog down their computer with multiple windows, programs and memory intensive processes, the 64-bit versions will serve them well.