Slow Macbook Pro

Hello,

I'm a mac user since october, i bought a macbook pro 13.3 inches, intel i5 2.3 Ghz and 4 gb of ram memory. I was so happy with this machine, however, yesterday all started bad, it is so slow when i go to safari i take around 3 mins to loas google web page (while in my ipad it take 5 seg, so it's not the wireless connection) when i press the launchpad button it takes a minute to load all the icons, when it is supossed to be immediately. Even worse when i try to used Microsoft Excel o Iphoto or any other application it take too much time to be ready for use! i don't understand what is happening the machine was working perfectly but suddenly it is not.

Thanks for your answers and suggestions!!

Ivan Suarez