If the installation file is normal and the operation steps are correct, there will be no conflict in theory. Even if you like, you can install sql 2000, sql 2005 and sql 2008 on one machine at the same time. But in the process of installation and use should pay attention to several problems:

(1) Neither SQL 2000 nor sql2005 should use the default instance name, and the instance names should be different.

(2) Installed. If you want to use remote login, it is best to set port numbers for two instances separately, instead of using dynamic ports and default ports.

Mouth 1433.

(3) Use authentication (sa) when logging in, instead of using the default windows identity. It may cause some unnecessary trouble. At the same time, start the sql browser service to facilitate remote control and connection.

(4)sql 2000 cannot access the database of 2005, and 2005 can access 2000. So it is convenient to operate across instances.

If you have any specific questions, please ask!