Upgrading PC using HDD from old PC

I have two PC's.  One is a PII the other is a P3 that was my wifes.  I want to take the HDD from my PII and install it in the P3.  The system won't boot (even in safe mode) because of driver problems.  How can I make this work.

Thanks

One thing to do (with the hard drive you want to use) is to boot up with a windows disk and repair windows. This basically reinstalls windows and keys it to the new motherboard.

Another possible thing is to make it a slave drive to the old hard drive.
Then log in under administrator.
Then right click on the slave drive and go to properties.
In properties there should be something about security.
You need to reassign ownership of all files to any user.
Then you can move files from one drive to the other.

I want to take the HDD from my PII and install it in the P3.  The system won't boot (even in safe mode) because of driver problems.  How can I make this work.

Seriously, how can you make what work?

I get that you want to use the Pentium III computer (the faster more powerful computer).  Not clear on how you want to use the hard drive(s).  Do you want to use both hard drives or just the hard drive from the Pentium II?

What operating system was on the Pentium II?  What operating system was on the Pentium III?  Which operating system do you want to use now on the Pentium III?

Which system won't boot (Pentium II or Pentium III)?  Is it the Pentium III that won't boot from the Pentium II hard drive because of (motherboard?) driver issues?