Hi Kshitij17 ,
Unfortunately windows itself will take up most of your 1gb of ram to run , any games you play will be laggy or slow if they can run at all
More ram is advisable however the amount of ram you can use depends on two things.
What operating system you are running ( a 32bit or 64bit ) version of windows
with a 32 bit operating system windows will only recogniise a bit over 3gb no matter how much ram you install , this is the limitation of a 32
bit operating system , whereas with a 64bit operating system the amount of ram you install will be all available for use
The second thing is the amount of ram your motherboard can physically take
can you tell me what motherboard you have and what operating system (windows version ) you are running and 32 or 64bit