I have over 100 computers that I need to format. Do you have an idea to complete the transaction as quickly as possible? (The best of them all at once). For information computer farm is a mix between windows 98, 2000 and XP.
Operating system is irrelevant here as it will need to be done at boot or outside from it, if you are talking about formatting the main hard drive.
I would recommend Darik's Boot and Nuke and use it on a USB drive, simply plop it in a machine and start, then move on to the next.
Alternatively, if you don't mind a bit of setup and these machines are networked, you can look at deploying Boot and Nuke to a PXE server and use TFTPD32 on Windows or any PXE server on Linux then you will be able to launch Dban across the network - just be careful that this is separated or other machines are not able to boot from it!
Do you mean format or do you mean wipe completely?
The reason I ask is that it sounds like you're trying to wipe them prior to getting rid of them, if that's the case then I'd recommend you did more than just a format as your data could be recovered from a format quite easily. If you do need to wipe them then you really need to send a little man around with something like norton system tools making sure the data is properly wiped ok.