Can the LG Xnote RD405 laptop intially with 1gb RAM be upgraded to 4 gb using two 2gb RAM's ? Please help me by providing an answer clearly, Thanks in Advance.

Here is the memory specifications from LG.

Maximum Size: Each slot is 1024MB and can be expanded to 2048MB.
SO DIMM Type for Memory Expansion: DDR2 SDRAM SO-DIMM (256MB, 512MB, 1024MB)

It can take a maximum of 2 gigabytes of ram. It will take two 1 gb sticks. It uses DDR2 laptop ram. You need to check to see if you have one stick that has 1 gb or 2 sticks that have 512 mb each. That will tell you if you need to buy one or two sticks of ram at 1 gb each. You will be able to tell a difference going from one gb to two gb of ram. I think it would be worth the investment if you plan on using the computer for another year or more.