Ok, Oldversion and oldapps only offer really old software versions which
are not supported I think.
So for Skype 7.3 I had to restore my Dropbox link.
https://dl.dropboxusercontent.com/u/4752212/SkypeSetupFull-7.3.0.101.exe
For preventing updates I don't know, I found a program which should do
so but I have to verify if it works, mostly because it's on an Italian
website and I need to make sure if it's language-dependent or something
like that.
Bye!
Barbuz