Understanding the impact of RAM on overall system performance

WindowsNetworking.com - Before I get started, I want to point out that this article makes a couple of assumptions. First, I am assuming that you are running either Windows 2000, Windows XP, or Windows Server 2003 on a 32-bit computer.
The second assumption is that the computer in question is relatively new, and isn't grossly underpowered. The information in this article may not hold true for other versions of Windows, 64-bit systems, or for computers that are grossly out of date.
Windows and memory
One of the main reasons why memory is such an important resource has to do with the way that Windows makes use of it. When the first version of Windows was created, memory was tough to come by. Memory was expensive, and even if you could afford it, computers at the time were very limited as to how much memory they would accept.
Even as recently as the mid-1990s, memory was still a huge issue. For example, my first Pentium computer came with 8 MB of RAM and supported a maximum of only 64 MB. This may seem ridiculously small by today's standards, but at the time memory prices of as high as $50 per megabyte were not uncommon.
The high prices and limited motherboard capacities made memory a scarce commodity to say the least. Because of this, Microsoft has always allowed Windows to rely on virtual memory to some extent. The idea behind virtual memory is that since hard disk space costs so much less per megabyte than physical RAM, Windows could use hard disk space to compensate for shortcomings in the system's RAM.
Virtual memory seemed like an ideal solution in the early days of Windows, but there were some drawbacks to using virtual memory that still hold true today. One problem with using virtual memory is that the hard disk is much slower than physical memory. In fact, memory access times are measured in nanoseconds, or billionths of a second. Hard disk access on the other hand is measured in milliseconds, or thousandths of a second.
Another problem with virtual memory is that it isn't directly usable. For example, suppose that a page of memory is written to virtual memory and then later, the computer needs to access that page of data. The computer can't access the data directly from the hard disk in any meaningful way. Instead, the page of data must be copied to RAM before the computer can work with the data. This process is known as paging.
As you can see, paging

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