Backoffice4.5 in place Mig to Backoffice

I currently have a NT Backoffice 4.5 server which runs exchange 5.5. I want to do a inplace upgrade to Backoffice 2000. I have two questions. 1. My server name has a underscore in the name Example name_12 Will this cause problems will Windows 2k following the upgrade. and 2. What are the common problems that are occuring on this type of inplace upgrade.
Barry p