Hi, thanks for the reply. This is what I tried:

-set ORACLE_HOME=d:\oracle\product\10.2.0\db_1
-set ORACLE_SID=orcl
emca -config dbcontrol db -repos create

This is what I get:

STARTED EMCA at Dec 26, 2010 8:48:21 PM
EM Configuration Assistant, Version 10.2.0.5.0 Production
Copyright (c) 2003, 2009, Oracle. All rights reserved.

Enter the following information:
Database SID: orcl
Dec 26, 2010 8:48:26 PM oracle.sysman.emcp.DatabaseChecks checkDbAvailabilityImpl

WARNING: ORA-01034: ORACLE not available

Dec 26, 2010 8:48:26 PM oracle.sysman.emcp.DatabaseChecks throwDBUnavailableException

SEVERE:
Database instance is unavailable. Fix the ORA error thrown and run EM Configuration Assistant again.

Some of the possible reasons may be :

1) Database may not be up.
2) Database is started setting environment variable ORACLE_HOME with trailing '/
'. Reset ORACLE_HOME and bounce the database.

For eg. Database is started setting environment variable ORACLE_HOME=/scratch/db
/ . Reset ORACLE_HOME=/scratch/db and bounce the database.

Any ideas?

Thanks