I have already installed Windows 7. So I am not installing anything.
Windows 7 was working perfectly until one night i received the BSOD. And shortly after a 'memory dump' was in process.
The morning after, I went to start up my laptop.. and when it reached the "loading windows" animation.. it would stay there and not do anything at all, its as if my hard drive isnt active :S
I tried repairing the computer with "Startup Repair" and "System Restore" but had no luck.
I also tried running Safe Mode. But every time, the bootup of Safemode would freeze at Drivers/CLASSPNP.SYS
I had a very similar problem when i upgraded my sisters HP Media centre PC from Vista home premium to vista ultimate turns out it was the OEM slic in the bios preventing the booting of vista ultimate even safe mode wouldn't work it caused all kinds of problems from locking up at starting windows screen to outright BSOD's even though it installed just fine. going back to vista home premium and problem gone no more booting issues no more BSOD's it turns out that HP locked the slic to only allow vista home premium
I had the same problem with my Windows 7 upgrade from Vista.
The way I fixed it:
1. Unpluged all USB devices except keyboard and mouse.
2. Rebooted PC from CD. Be patient here, it takes a while to start (hours);
3. Restored to previous restore point (5 days ago). Waited for full night, and in the morning everything was fine.