From my experience with COMPAQ's, what you may have run into is one of their proprietary "Tweaks". The COMPAQ PC's that I have worked on have a special little code on their hard disk drive (HDD). That code must be there when you run their system restore CD, and since you have a new HDD, it is not.

One solution that I would suggest is to hook up both HDD's, boot from the floppy that probably came with your new HDD, and use the drive copy utility that is on it. (I may be assuming too much here, but all of the HDD's I have installed lately have this kind of utility). Configure one disk as a Master and one as a Slave on the first IDE controller. Instructions to do this should be with your new HDD. After you get your old drive copied to the new one, you can configure the system anyway yo
u like (i.e. take out the old HDD and just use the new one, use both with the new one as the Master, etc.)
COMPAQ's web site will probably have some more info on your situation.

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