For anyone still having issues, you might try right clicking terran.exe (or the shortcut) and running it as an administrator. Only way I could get the directdraw trick to work :)

In case anyone was wondering, yes you can, kind of.

Open a copy of SMAC
CRTL-ALT -DEL to go to task manager. Really you just want a way of accessing your desktop/files again, as you cannot alt-tab out to the desktop (to change music or, oh i don't know CHECK THE TIME o.0)
Open ANOTHER copy of SMAC. You should now have two Alpha Centauri games running.
Quit one of the games.

The other game should now be in a borderless window. You cannot use the mouse to scroll now, however, as the mouse moving along the edge will now continue onto the desktop so you can switch youtube videos or whatever.

I don't know if this is compatible with the direct draw thing above. I did not make any changes to the .ini and am running the GOG version

Okay, the disabling of DirectDraw makes it run at native, but that doesn't bring ALT+Tab back. :U

The SMAC Wiki contains an article that describes how to enable Alt-Tab:

http://www.gogwiki.com/wiki/Sid_Meier%27s_Alpha_Centauri#Restoring_Alt.2BTab_support

Much obliged. I forgot about the Wiki.

There is a simple way to launch SMAC in windowed mode. You need to download DxWnd (OG edition).

I ordered a DISK from UK and it runs with no problems on WINDOS 7.

Is there a way to run it windowed mode without installing a custom program?