I would not mention "Packard Bell" if I were you.
So did you take out the old HD and replace it with the new(er) 2.5 GB one? If so, did you set the jumpers on the newer one for Master?
It's not clear whether you were actually able to access that newer HD and to fdisk it. After FDisking it, you need to format it or you won't be able to access it from your OS, but BIOS will still report that drive as found.
You
can access BIOS on your
Packard Bell, can't you?
Depending on your OS, you may need to actually partition it into several partitions so DOS can recognize it. Also, your BIOS (your
Packard Bell has
BIOS, doesn't it?

) may be too old to recognize drives that large. You will need to either flash it or to get a special program to be able to use it. Western Digital provides such a program, but I don't remember the name.