How to check if an application is installed

[MattWilkinson]

I have a couple of pre-requisites that I would like to check for before starting the installation (one is Crystal Reports runtime 2008 and one is Pervasive Database).

I was thinking that if I could check through all values in the HKLM\\SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Uninstall section of the registry that I could see what is installed. Is there a better way of doing this?