w7 unusable after install

Hi Im new here and Ive got a problem.

I upgraded my main computer from vista 64 to w7 64 few days ago. I did perfect clean install everything went like in the guide given in these forums, although it was kinda slow process like 1-2 hours. I have clean installed w7 few times after, it always installs fine but slowish.

The problem:

Starting the computer and entering the desktop takes about 10 minutes. When on desktop clicking anything causes freezing for 100s of seconds (!!!), finally it does my command though. But I cant open any program, folder or internet because it will just lag and say "not responding". I can do pretty much nothing. When ctrl+alt+del I get screen saying: "Failure to display security and shut down options. The logon process was unable to display security and logon options when CTRL+ALT+DEL was pressed. If the operation system doesnt respond press ESC or restart the computer by using the power switch." So Im stuck at step 19. because its impossible to install drivers and stuff.

It is like the processor would run 99,9-100% all the time. It is unusable. Theres no outer devices connected except P/S2 keyboard. It doesnt make a difference whether internet is plugged or not. I gave it time over because I thought it was maybe loading something, but no difference there in the morning. After many restarts the problem still occurs. Vista ran perfectly before btw, cant be a hardware problem.(?) Got Packard Bell iPOWER x2.0= i7, nVidia GT230, 8Mb DDR3 or something like that.

Any helpful suggestions are appreciated Im really outta clue here. Gosh I just payed +100 euros for making my computer from fully functional to completely unusable.

ditto what others have said:
Clean Install Windows 7 - How to Perform a Clean Installation of Windows 7 - Part 1 of 3

Thank you very much for help

But its still the same problem. The Bare Foot kids advice was probably the best as I already had done quite few clean installs. So I followed his guide with method two cleaning HD to 0Mb and then clean installing w7 from my USB-stick. No difference though, the same problem started over again, when I put my name and set clock and stuff the painful waiting started. (untill that it went smooth) I managed to get to desktop, but still the same problem.

So I whiped my USB-stick clean and loaded new ISO 64 w7 file from Microsoft (with my laptop) and installed it into USB again (so the problems not there?) -> then I followed BFK´s guide second time, whiped HD -> clean install -> smoothness untill I had to put my name and stuff. I also let desktop be 24h open after that in case of loading or processing files, dont know was that vice...

Ask me questions and Ill answer I dont know what I should tell.

Then theres this 1 thing, I am pretty sure my vista was 64-bit version, there was program files 64 folder and I was told it was 64, Im starting to question my own memory here . But anyways the thing is when I tried enter safe mode there came this white text on black screen for a sec that said something about loading drivers32, many times different drivers all drivers32. Ive never had 32 OS how in hell I have 32-bit drivers? Thats the problem?? But should It even matter what OS I had if I whiped HDD?