He He, You have to ask three different people for advice then pool the responses and get them to agree on which of the three conflicting answers is correct. I had great difficulty getting a sensible answer about how to licence a new dual core, dual processor SQL server 2005 box and I still haven't had a response on the BackupExec remote service yet.
/rant
It is correct though that MSDOS does not come under the upgrade rules.
HBJB