skype - really portable and is it genuine?

i see there is a skype portable. when downloading, it starts with a 1mb-ish file. i didn't even bother when i saw that. that bit tells me, it's going to try and first use a web installer (the 1mb file) and then, maybe, get the "proper" exe. that's not really how it works for 99% of the apps here so.. yeah..

i'm already weary that there is a portable skype since i doubt microsoft wants that and is actually involved. i mean why would they? with the full windows version, they get to install drivers/hooks and whatever they want really (especially since they created the o/s).

still, if there truly is a proper portable skype, i would like to use that. if there is, and the setup file is a singular executable (not lose files) that is digitally signed by Skype Software Sarl / Microsoft Time-Stamp Service and is valid, i will look at it.

and if anyone here has already used the portable skype linked from here. is it truly portable? you extract/install the files and just place them into a directory and run skype and it works? or do a whole bunch of "things" still get installed/hooked into registry/etc? skype is i think a somewhat advanced program for what it does, so having a truly portable version -in principal- i already find suspicious.

thanks,