I don't use my computer much.. Its only for internet browsing.. checking mails and bit a word doc works.. Should I upgrade RAM?

Always try to buy the largest single stick of RAM that you can, within reason. For instance, if your computer has two memory slots on it and you want to put 512 MB of RAM in it, you have the choice of buying two 256 MB sticks or one 512 MB stick. The 256 MB sticks may be a few dollars cheaper, but what happens if you want to add more RAM later? You're out of slots. If you have two memory slots, buy your RAM in 512 MB sizes. However, if the motherboard has three or four memory slots, you can get away with 256 MB sticks of RAM.

http://computermemoryupgrade.net/how-much-ram-is-enough.html