Well, complaining that you haven't got an answer after only 1 hour or so, it's a bit extreme and, just to put this in perspective, it's 10:02 PM here now...
In any case, you can find the installed version number in the Windows Control panel, under the Add/Remove Programs section. Not that this really matters to GSX, since there's the Live Update, the version number it's not really something you should worry about, if you are current with the Live Update, you *have* the latest version, regardless of the version number.
The only things that are not coming with Live Updates are the additional vehicle liveries, which you can download separately so, even if you had installed the original 1.0 version, with the Live Update and with the additional vehicle liveries, you have the same version as someone that downloads the 1.2 installer today.
