SPYWAREDr
I already done that before posting this issue.
but when I removed the disc and pressed any key it does reboot alright but nothing happens, just a black screen. After the reboot (=Dell fast boot)
That idea is not so good, and here is why!
I've loaded win xp the same CMOS setup with no problem,
and furthermore in a normal clean install, after pressing any key the cd\dvd rom commence installing the setup files etc etc.
Then when all the necessary windows files are loaded windows will reboot (it will tell you so)
Now the press any key screen appear again ,
but now one must do nothing and just wait!
A few second later the system will reboot by default.
now the hdd see that it has a operating system to load, to the hard drive, the win video driver and most of the files necessary that tell it to continue loading,
now windows start loading hardware drivers,system file etc,etc. I know that you know all this,
I'm saying this just to make my point.
I understand what you are saying, that is to change the CMOS Setup after the win 7 files are loaded so to force the hdd to boot first and then presumably if it does, the set up will continue loading windows.
At a first glance your suggestion doesn't seem to hold water,
but I'll give it a try just to see if it works following your logic.

The CMOS setup is as follows:
first boot device is cd\dvd rom,
second is hdd 0.
there are others,
the two that concern us are this two.