The RAM can slightly improve the computer performance when they are paired in size and speed, running a feature called "dual-channel", so if you can change the 2GB module that your laptop has and put on its spot a 4GB module with the same specs than the other 4GB module, you will get this feature and additionally a little more room if you use to have tons of applications or tabs in the navigator opened and that kind of stuff. Anyways formatting the PC is a cleaning that will definitely improve its performance and changing the hard drive for an SSD will dramatically improve it.
Anyways, the laptop con reduce its performance if it is being overheated because of accumulated dirt on the cooling system, you can check this installing Speedfan and looking there the CPU cores temperature, which is bad if being over 70ºC when only navigating, watching movies or the mail, that kind of stuff. If there are temperature issues, opening the laptop to clean it is easy but you can always ask for professional help, and also for the RAM and SSD upgrades, but could be a little expensive.