VS 2010 - Get Installed Software From Remote Host. Win Vista/7?

I have created a Windows service that runs on one of our servers. The service lisens to incoming connections on a set socket port, runs a series of WMI queries on the requested computer in a new thread (the socket accepts a string value as input which is the hostname to scan), creates an xml file based on the collected data, and posts it back to a webserver. This works perfectly on all WMI queries, but i have one function that gets all installed software from the requested host using the RegistryKey.OpenRemoteBaseKey method to get all keys from the "SOFTWAREMicrosoftWindowsCurrentVersionUninstall" key on the target host. If the the target machine OS is Window Vista or 7, it returns no values. If i run this code on the target machine it works, but not from the service on a server. The service is installed and runs with full domain administrator rights. I guess this is a permission issue, but i have not found a good solution on how to solve it on the internet. As a workaround i use WMI to get a list of installed software from computers running Vista or 7. The problem with the WMI method is that it's very slow. It takes 10 - 15 seconds just to loop thru all ManagementObjects in the Querycollection. Maybe i could filter the WMI query better before starting the loop ?

[code]...