When things on the computer start moving at a snail's pace, it is time you did something about the RAM on you computer. It is one of the most important parameters, that decides the speed of performance of your computer, other than the chip processing speed.
Random access memory is the 'Working Memory' of the computer. It decides how many applications can be handled by the computer, at a time. Hardware wise, it is a different type of memory, than sequential memory that you find in the computer hard disk.
That is why, it is faster than sequential memory. It is installed in the form of a separate integrated circuit on the computer motherboard. The parameters to look out for, in a RAM, are data transfer time, which is usually in nanoseconds and its memory size. Lesser the data transfer time and more the memory size, the better it is for your computer.
If you are looking for a multitasking computer or a computer which will act as a web server, then you need a bigger RAM in both cases. The extra memory makes multitasking very easy.
A straightforward way is to install extra RAM. This will certainly increase the speed of computing and enable you to run more programs, which includes graphic intensive gaming applications.
Generally, most operating systems need a minimum of 1-2 GB (Gigabytes) of RAM. You need to decide how much of an extension you need, after taking into consideration, what kind of operating system you are running on the computer and what are the kinds of applications that you are going to run.
Another way of increasing RAM, is to cut down on the applications you are running on the computer. However, installing extra memory is a much more long-term option, which you should go for.