Oracle 8i and 9i Database concurrently on Windows 2000 Server

I am trying to install Oracle 8i and 9i Database server on same machine , but I am getting getting various errors..

I cannot start TNSListener servive of both 8i and 9i simultaneously. If i try to login to 8i Database using scott / tiger or try to create a database , I get "Tns protocol error".
Cannot complete Net8 configuration and Database configuration while installing 8i Database server.

Please help me for same as i tried installing 8i for many times. I have kept different home names for both 8i and 9i. Forms 6i and D2k 4.5 is already installed on the M/c. Is there any sequence for these installations. Received on Thu Feb 23 2006 - 00:26:18 CST