I used to create basic installers for PPC manually and spent weeks looking for a better solution. Eventually I was told about some software that does pretty much everything for me, including building the cab files etc. Take a look, it's very cheap for what it does and youd be hard pressed to get an installer looking more professional with any software, even if you spent hundreds......
Pocket PC Installation Creator (by Aperitto Software)
http://www.aperitto.comI tried the demo and it wasnt long before I bought it, great software.