Hi Nana.
While i know that those sites provide a fully portable access to messenger, i must point that those are web-based applications, and has many weak points (such as ad banners, the way the windows are created (they're still IE / FF windows, can't hide in the systray), and so on)...
I used them a couple of times, but their accesibility is pretty limited... That's why i started looking for real portable applications, and not those web-based one
thanks anyway, but that's not what i'm looking for...