Now just a minute. That is not how you answer OP's question. OP asked if he can upgrade to 4 GB, not asking for any that type of program.
To OP. It might be helpful.
http://www.intel.com/content/www/us/en/chipsets/mainstream-chipsets/g41-express-chipset.html
You can installing 4 GB on your computer, but there is small problem. It is old chipset. It might will shown only 3.5 GB to 3.8 GB usable.
If RAM had reached limited of RAM support then it won't shown all of your computer memory on system information.
Such as "Installed memory (RAM): 4.00 GB (3.87 GB usable)"
For EX: If you installing more than 8 GB RAM and you have windows 7 32 bit, what happen? It will say 3.5 GB usable.