EEPC
Newbie level 6

Hey guys,
My friend who works at this company donated to me a couple old Dell Optiplex computers in his group that have been obsolete for a few years and subject for disposal soon. I would like to turn them into cheap workstations -- afterall they can still run most engineering software decently albeit slowly. The only problem is that they still have the old network passwords installed, so when booted up they go to the Windows domain login screen (not sure if this is the correct term?), and of course I can't get access to the system since the passwords have been lost long ago. I've also tried booting into safe mode and logging in as Administrator, but that has not worked either. To further complicate the process, the computer is incapable of booting from the CD drive so I can't just install a new operating system.
Would I be able to get around the login issue if I just replace the old hard-drives with different ones?
Thanks for the help.
My friend who works at this company donated to me a couple old Dell Optiplex computers in his group that have been obsolete for a few years and subject for disposal soon. I would like to turn them into cheap workstations -- afterall they can still run most engineering software decently albeit slowly. The only problem is that they still have the old network passwords installed, so when booted up they go to the Windows domain login screen (not sure if this is the correct term?), and of course I can't get access to the system since the passwords have been lost long ago. I've also tried booting into safe mode and logging in as Administrator, but that has not worked either. To further complicate the process, the computer is incapable of booting from the CD drive so I can't just install a new operating system.
Would I be able to get around the login issue if I just replace the old hard-drives with different ones?
Thanks for the help.