Thanks for all the replies sofar, much appreciated that people are trying to help with

this issue, even though I haven't found out what can be the problem :)

To Josh: yes I was aware of the 32-64 bit difference when I downloaded the ISO.

Could there be something wrong with another part of te computer (besides the hard drive that I replaced and the memory that passed a test) with the message I mentioned earlier:

Windows failed to start.
File: \windows\system32\boot\winload.exe
Status: 0xc0000001
Info: The selected entry could not be loaded because the application is missing or corrupt.

I am starting to get a bit worried with all the time I have spent on the
issue so far ...