Hi
You can also find the ID in IBM Cognos Configuration:
1. Start C:\Program Files (x86)\IBM\Cognos Express\bin\cogconfigw.exe (if using Cognos Express)
2. Go to Security / Authentication
3. Click on Cognos Express and you will get the ID, which is, as Martin said, CognosExpress.
p.s. About replication and Cognos Express, you should be aware of this (it might not apply to you):
http://www-03.ibm.com/software/sla/slad ... 230048B42F
"Specifically, Licensee is not authorized and receives no entitlement to access or use the replication technology available from the IBM Cognos Express Xcelerator User module to create distributed applications."