Thanks everybody!
@Cameochi: Thank you, clever idea! (and again: just why didn't I think about this myself, I wonder...
I'm saving all my Stardock receipts in a special folder in Thunderbird and I'm backing up Thunderbird regularly, so everything is there... the only explanation I have is that I'm elsewhere with my mind at the moment, the FIFA World Cup for example and the second semi-finale match tonight
) By the way, you will get the updated version for older skins as well when clicking the link on the stardock receipt, I tried it with MikeB314's Sirus-Blind.
@Jafo: Thank you, too, and yes, I know that as long as I use or in this case modify other peoples art only for myself I won't need permission. But I also had in mind to maybe upload a ported VS here if the results (of my attempts) would have been good enough - some of these msstyles are really good work, though they are not as complete as WindowBlinds skins (and I somehow doubt that my skills would have sufficed to complete a ported VS in a way that it would have made a Blind good enough to share, but in that case I'd have asked for permission of course...).
@Island Dog: Great, thanks, this link is just what I needed (and Cameochi's idea is working as well, of course). I have to admit I forgot how well organized Stardock is...
@DrJBHL: 