If you have ever noticed that your computer is slow when switching between applications this could be because you are short on RAM and information must be copied from the RAM to the hard drive to prevent it from being lost. These swap files move back and forth from the hard drive to RAM as needed. This process is very inefficient and slow as you can imagine putting files back into the cabinet before more files can be removed would be.
There is, like all things, a limit to this as well. If you have ever received a message saying that you are low on virtual memory then you have reached the limit. There is a limit set by the operating system based on the amount of RAM available as to how large the swap files can get. Once that size is reached there will be a warning and eventually the computer will be force to restart because it has run out of resources.
Adding RAM to a computer is like getting a bigger desk. There is now more room to work efficiently without having to move back and forth between the desk and file cabinets. This makes switching between applications much faster and the computing experience more enjoyable.
There is, however, limits to how much total RAM can exist on a system. Windows systems operating at 32 bits are limited to 4 GB of RAM. There may also be limitations of the hardware as well. Some motherboards may only support 2 GB of RAM. So before upgrading be sure that your system will support additional memory. Also keep in mind that even though Windows 32 bit claims to support up to 4 GB of RAM only about 3.5 is recognized by the operating system as usable memory. Windows 64 bit operating systems do not have these inherit limitations and at this time will only be limited by the hardware.
Another thing to keep in mind is the speed of the RAM. When purchasing more memory look at the sticker on your existing stick. Be sure to purchase the same speed and type. Say your current 2 GB stick of RAM has a clock speed of 1333 MHz and you add another 2 GB stick with a clock rate of 1066 MHz. The motherboard will down clock both to operate at the slower speed.
So before buying RAM be sure that you have a physical port available on your motherboard and that the RAM you are adding is the same speed and type in your current system. Adding RAM is very cheap and will usually make a noticeable difference in day to day use.