check any software installed on client computer

[Furtbichler]

Zitat von question:

is it possible to check whether a software(skype) is installed on the client machine

Zitat von Luckie:

I don't really get what your problem or your intention is.

To be honest, it is very clear in my eyes.
However, besides Luckie's answer (which would cover most apps) you would have to search individually for each software. Most of the application will use the registry somehow so you could check for a specific entry. But you'd have to know which one to look for.