I am currently working this same problem out with a laptop.
When I received the laptop, the HDD was fried.
I replaced the HDD, ran some scans to make sure the HDD was efficient, and began my install of Windows XP Professional. The laptop the HDD came out of had a copy of XP Pro on it when I began, but gave me BSOD before Windows began to load.
My first thought was, just some random error. I'll worry about it later. (error code 7)
I began doing research, and I strolled across archives of forums with the same problem, almost all of them saying, "check your RAM". I've never worked on laptops before, so I'm new to these problems. I'm not sure if this is a laptop only problem. Its not uncommon for the desktops I work on to have bad ram. I'm not sure what this person managed to do to fry both the HDD and the RAM at the same time, but here I am.
One forum I found linked me to www.memtest.org . They said make a boot disk from this website and run the tests to make sure all is in order. It will take some time, unless you receive errors immediately. Any errors will lead to a bad set of RAM.
I will be testing this problem when I get home and will keep you updated on my progress.
Feel free to e-mail me if you need more help.