Do you have any budget where you can just buy a whole new computer? Because even a low end pre-built (aka, Dell, HP, etc) will be a great deal faster than what you have. It really isn't worth upgrading unless you just don't have the money for an all new computer.
Also, you have 4 GB of RAM in your PC, but I assure you the computer isn't telling you its 3.62 GHz
. It is 3.62 GB, meaning that of the 4 GB of RAM you have, 3.62 is all that your computer can use. Most modern computers can use greater than 3.62 GB of RAM.
Edit: Also, you can't use DDR3 RAM, so the RAM you found is useless for your computer. At best, your computer can only use DDR2 RAM. Again, this is yet another reason to steer you towards just buying an all new computer
. I assure you, for about $500 - $600, you'll have a super fast PC.