Ghosting the same HP computers?

We bought 200 computers(HP Workstation XW4400 with Windows Buisnes OEM)
to our computer lab.
For first 8 weeks we was running Windows 2000 pro (so called
downgrading) on all computers, because I did knew how to ghost and roll
out it. No activations and such things. Just make ghost, ghost all
computers and run ghostwalk on all of them.
Will work?
The HP machine come with Windows Vista already activated. Can I ghost
from one such machine to all others with the same hardware or not.

Can I install one machine with original OEM Vista and ghost it the same
way Windows 2000 I done. Then rollout and run ghost walk.

Will ghosting work this way????
Need help ASAP


Regards
Marcus