That is so weird. I had the exact same problem. Installed GalCiv2: DL, updated to 1.53 through Impulse, but the game would just hang after hitting the Play Game button on the start up screen. I had to Ctrl-Alt-Del the game. So I tried LujanD's 'technique'
and it's working fine for me now.
My res was 1440x900 on 2 monitors. So I turned off my secondary monitor and changed my primary's res to 1024x768, started the game and it started in seconds. Then I exited the game, turned on seconard monitor and changed res back to 1440x900, then started the game and it works fine now.
There seems to be something between fresh installs and primary monitor resolution.
My specs:
AMD X2 4200+, 2GB Ram, GeForce 7300 GS, Win XP SP3