Specs: Intel Core i7 720M
Windows 7 Ultimate x64 bit Genuine
8GB DDR3 RAM
ATI HD 6870 Graphics
It doesn't matter what plan I run my computer on, my computer (sometimes) can be extremely slow. Whether I have only Firefox open or I'm playing a lightweight game on Low graphx, it doesn't matter. I have 0 viruses (I have Norton and I did a full scan 5 minutes ago). My HDD is fine only around 100GB used (1tb memory). Please let me know.
PS its not overheating. I have a cooling pad on when I use it and I installed diamond cooling.
Tempted just to say that Norton is killing your machine. I once installed it on an overclocked dual core machine, 4GB ram and SLI (old rig now) and it brought it to it's knees every few hours. I ended up getting rid of Norton (for good) and using AVG - no more issues.
Make sure Norton doesn't have any type of auto-scan or auto-update settings active as I know it LOVES to update itself randomly which it somehow makes one of the most CPU-hungry operations.
You might also want to disable any automatic "under-clocking" settings in your BIOS so your CPU doesn't randomly drop.