My PC running slow

[Serar]

I have a PC with windows 7 installed, Intel Core 2 Quad Q9400 cpu, nvidia 9800 gt graphic card and 4gb ram. I had an issue with the hard disk (bad sectors) and changed it so it's like I did a format. I installed the windows and microsoft security essentials. I use Google Chrome. The matter is either before or after I changed the hard disk if I had 2 processes or programs at the same time opened my pc would freeze and run very slow. When I say 2 processes or programs I mean like WMA and Google Chrome, or Utorrent and Google Chrome or WMA and utorrent. 1 year ago my pc was running smoothly no matter what I was running. I guess its not a problem with the windows. I am thinking that it could be the BIOS. How can I make my PC run like the old times?:shock:
ps: my total memory is 3326 and it says that cached is 1504 available:1769 free:293

 

[ThrashZone]

Hi and welcome to SevenForums,
I wouldn't be using Microsoft Security Essentials without a premium subscription to Malwarebytes as well,
It's either that for look into Panda antivirus instead of not in addition to MSE,
Cheers.