Hans,

I would install Win2K only if the final place where the database will be running is Win2K.  As far as detaching from SQL2K to SQL7 system make sure that the database is in 7.0 compatability prior to detaching from SQL2K.  Also, you need to make sure beforehand there is no code that takes advantage of any new features that were added in SQL2K.

As far as performanceboth should act the same.  Only difference should be concurrent users...

Of course I may be wrong and the gentlemen and ladies that have been using SQL for MUCH longer than I will set me right as always to keep me from hurting myself