Slow install and extracting on new inspiron 7110 notebook.

Hello. I have recently bought a Dell Inspiron N7110 notebook with the following characteristics : intel core i7 2nd gen 2Ghz , 6 GB DDR3 1333Mhz , 640Gb HDD with 5400rpm and 2Gb Video Nividia GT 525M. The notebook is great when in comes to gaming but I there is something that bothers me. When extracting with Winrar a 8gb file it takes a long time to complete it. Same thing happens if I install some programs/games. Sometimes the install window does not respond for a 2 minutes and takes way longer than my PC,  which is very old , to complete .Also the Cpu meter on my desktop always remains at 4-7% so I don't think it's from CPU. 

And if I try to install for  example Dirt 3 and extract a 4gb archived file at the same time , neither of them complete even after an hour+. Maybe I am having very high expectations from this laptop , but I consider this to be a problem. Also I am hearing sometimes a wierd sound comming from it. The sound is just like the one that happens when the Cd-rom can't open / is jammed or something near this ideea. But the dvd-rw from the laptop works perfect.The sound appears ussually when I reupdate my drivers or when I enter some games. I am thinking that it may be a problem from the HDD?Is the device causing this sound and the other problems? Should I go back to the store from where i bought it and ask for a new one ( or money back  even though I don't want to , I really like this notebook).