1 MONTH OLD iMac keeps freezing and running extremely slow.

I have this new iMac, its about a month old now, and it keeps freezing and running really slow, even when I am only running Safari and Microsoft Word! it is running the newest version of Mac OS X 10.8.2. Sometimes I am only running Safari and it runs VERY slow. It has 4GB of RAM and a 500GB HDD that has 405.76GB left. In fact jsut as I was writing this post, it started to run extremely slow. I wouldn't even expect and old PC to run as slow as it was. Now it is running fine again after me almost ripping my hair out from frustration. I have a Macbook Pro that is over 1 year old and it doesn't do this. They both have the same software, hardware, and applications. Also sometimes this iMac makes a sound like it is boiling water. Is this normal? Should I take it to the Apple Store to see what they say? Thanks for any suggestions.