We just recently upgraded to SBS 2003 and now have a spare server with SBS 2000. Since our BES was running on WinXP I want to move it on our old server. If I only install the OS part of SBS (CD1) would the server still be considered a SBS server or would it be a plain 2000 Server that can be added to the Domain? I do have a seperate Windows 2000 Server CD/License, but for some reason it cannot format the hard disks/install.

Also, would I be violating any license agreement by doing that?

Thanks in advance.

In theory it should work - in both cases you would install a Windows 2000 without the upgrade to SBS2000. Regarding the licensing issue - I would recommend the safe way and call Microsoft about this. I can only guess, but I would expect that they say that this is not allowed.
The SBS 2003 license is a new one or an upgrade license of the SBS 2000 version?

To fix the issue with your other Windows 2000 CD that won't format the harddisk I would recommend to try to create a new CD with newer/updated storage driver and possibly slipstream Service Pack 4 for Windows 2000 into it by using nLite - Deployment Tool for Unattended Windows.