November Macbook Pro 15 lagging

[speedemonV12]

Hello,
I have a 15 inch Macbook Pro that I got in November of last year, and the past 2 months or so it has been lagging like crazy. Just doing simple tasks, like typing this message brings up the apple working wheel. I have 4 gig of ram, and i just reinstalled the operating system. Could there be something wrong with my hard drive that is causing the operating system to run slow? Any suggestions? Or should i just call up apple and let them try and figure it out?

 

[C64]

Launch Activity Monitor and check out what's in use when you experience these problems.

On top you'll see all the processes. Sort by CPU usage, descending, to see which is using most. At the bottom the CPU and System Memory tabs are important. Check to see how much memory is being used.