Windows 7 fresh install, incredibly slow and 100% CPU usage

I just installed a completely fresh windows 7. I wiped and formatted the hard drive prior to installation. For some reason the install took like 7 hours. And afterwards, it still runs horrifically slow. I checked task manager and it shows my CPU usage at 100%. I checked applications and processes, and there are very few there, and all are between 2-8% CPU usage. I'm not very tech savy so I'm just going by the number shown under the CPU column in the Processes tab. Also it says there are 33-35 processes running, even though it only lists about 8 in the task manager. I've only installed 2 things since I installed windows 7, and those are google chrome and microsoft security essentials. Before someone says that either of those 2 could be the problem, they were installed afterwards, and it was slow and laggy before then. Windows has supposedly updated all the stuff it needed to because it restarted and updated a number of times, and I'm no longer getting update messages.
I'm using an Intel(R) Core(TM)2 CPU E7500 @ 2.93GHz with 4 gigs of ram.

7 hours is a bad sign.

Go to the process tab of task manager and click at the top of the CPU column to rank the processes in order of CPU usage. Post a screen shot of what you see. Make sure you have checked "show processes from all users".

33-35 processes is pretty good.

I assume you have no anti-virus running currently?

Was the install from a known legitimate DVD onto hardware with no known problems?

Do you see any yellow exclamation marks in Device Manager?

Any known temperature issues?

i cant post a screenshot, when I say its horrifically slow, I mean its unusable. I'm typing this and browsing other threads on a different computer. Here's what it looks like though:
Image Name CPU
taskmgr.exe 44-47
dwm.exe 0-2
csrss.exe 0-2
explorer.exe 0-2
msseces.exe 0-2
GoogleUpdate... 0-2
taskhost.exe 0-2
dllhost.exe 0-2
consent.exe 0-2
winlogon.exe 0-2
wermgr.exe 0-2

i clicked the "Show Processes from all users" but its so slow theres no telling if it actually registered me clicking it, if it did anything at all, or if it did do it and thats all there is.
MSE is installed atm, but this problem was present before I installed it.
I got the disc from a student / employee supply store that sells to schools and colleges. When I installed windows and put in the product key that came with the disc, it was invalid. I called microsoft and got a working key from them (it took 5 hours to verify the key)
I can't access the device manager at the moment because it would take about 30 minutes to open it.
I've never had any temperature issues before.

When you said you wiped and formatted the drive did you delete the original partition (s)?

If not, I'd be inclined to make a fresh start and re-install Windows.

Delete any existing partitions and create a new one. There's no need to format it again, Windows will offer to create a 100MB boot partition and will automatically format the partition it is installed on.

You may also have to face the fact that you may have been given a bad disc.

If that's the case you can download a Windows 7 ISO from Digital River and burn it to a DVD for installation then use the product key given to you by Microsoft to activate Windows.

i wiped it completely using linux from my USB drive, and re-partitioned the entire hard drive in ntfs format

In that case, I'd seriously investigate whether you've got a bad disc or God forbid, a suspect hard drive.

The list of processes from All Users finally showed up and the top process was MsMpEng.exe which I know is an anti virus thing. I tried to end the process, but then my monitor went black.... I'm restarting the computer but it takes forever to start up with its lag.

I know windows 7 is a lot more than XP, but it was never even a bit slow with XP (and same hardware). So unless windows 7 is THAT much more demanding, I strongly doubt its a hardware problem.

Not entirely related, but I discovered recently that hardware faults can have unexpected repercussions.

After battling for six months to try and find out why my computer was taking up to 15 minutes to boot up, it turned out to be a faulty optical drive. I only discovered it when I ran a full diagnostic test and the drive failed the read/write tests.

Changed the drive and now my computer boots in under 40 seconds. All I can suggest is look for the unexpected, it can have a positive effect.