Your best bet, is probably to enumerate the registry MSI installers.
Located at: HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Installer\Products
For example,
I can see, for example:
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Installer\Products\0458E21399705D540AE2FD8BCF9AC3AC
ProductName key is SQL Server 2008 R2 SP1 BI Development Studio