There are 2 more threads in which people want to buy 4 GB and 8 GB ram
Brothers keep one thing in mind that rams only work when you open application
Here I give you a little detail how pc works with ram
You memory store the instruction of OS, applications and programs as well as the data ready for processed.
Ram plays an important rule in the processing of a program. But this does not means that more ram means more processing speed.
when you assign a task to computer the processor get the required data from the memory and then execute the instructions and then again save it in memory means all the application run in main memory but there isn't any location in main memory for saving the data permanent so main memory save the data in hard drive. Ram is the middle thing between the processor and hard drive but instructions are stored in ram only for a particular time.
In games and normal pc usage 2 GB to 4 GB ram is more then enough as mostly games recommend ram from 2 GB-3 GB means they hardly utilize 2-3 GB of your computer's ram. Whereas windows and all other running application hardly 1 GB.
the only advantage of more ram is increasing the performance of video editing and graphical applications like Maya, adobe, etc (the difference in these types of application is notable because video editing and graphical software utilize too much space from your ram to execute a application as long as you edit a piece of file or working on a big file you have to open/load the whole file in your ram so that software can easily work on it ). But in games and normal usage of pc like web browsing, watching movies, etc you don't need more then 4GB of ram(you can checkout google for checking the maximum memory usage of a program).
The easiest way to identifying the usage of ram for your pc is to check the ram usage through task manager and check how much ram is available for free then you can purchase ram according to your need
Usually I see people have 2 to 4 GB of ram and hardly have they used 2 GB ram so the extra space is just useless for them and believe me you can not see a notable difference in the performance of 4GB or 8GB unless you a professional designer or something.