Running SQL 2000 and SQL 2005 simultaneously

I have seen information on the web about running two versions of SQL at the same time on the same server but was wondering any tricks of the trade regarding it. The main recommendation that I have seen is to have SQL 2000 SP4 running first as the default instance (which is my current situation on a development server) and then install SQL 2005 as a named instance on it. Should the SQL 2005 installation place its files in a dedicated directory (ie, C:\SQL2005) as opposed to the default directory that the installation would normally write to, thus not overwriting any SQL 2000 system files? Any other recommendations?

Well directories of the core files (files needed to run SQL Server should be separated in different directories), for data and log files it depends. If you already established a physical structur of distributed data files and log files (to enhance performance due to split IO access) you should reuse this structure, placing the files on the disk using the same "logic" as you did for the other instance. If you did not do that yet, you can place the files wherever you want, I would just ot mix them up with the other (data-)files as it will ease the migration lateron if you keep them separately.

Jens K. Suessmeyer

http://www.sqlserver2005.de