I just now tried it and I get the same problem. Here is the log. I don't quite understand it...
-- [Application] ----------------------------------------------------
Name: Stardock Central
Path: C:\Program Files\Stardock\SDCentral
Version: 2.20.359, build: 103
-- [System Information] ---------------------------------------------
Platform: Microsoft Windows Windows XP, 5.1.2600 Service Pack 2
Display: ATI MOBILITY RADEON 9600 Series
Driver Version: 6.14.10.6546
System Dir: C:\WINDOWS\system32
Time / Date: 17:51:31 -- Saturday, January 28, 2006
-- [Installing] -----------------------------------------------------
Server: http://sdcentral2.stardock.com
Server Dir: public
Network Id: drengin
Name: Galactic Civilizations II
App Id: gc2
Installed: False
Version: 0.81a.015
Type: production
Reg Key: GalCiv2
Install Dir: C:\Program Files\Stardock\TotalGaming\GalCiv2
Exe: galciv2.exe
Last Updated: 01/25/2006
-- [Account] --------------------------------------------------------
First Name: Joel
Last Name: Halfwassen
Email: joel@interserv.com
-- [Installation] ---------------------------------------------------
Download: C:\Program Files\Stardock\SDCentral\data\public\gc2\production\gc2.xml 1
Load: C:\Program Files\Stardock\SDCentral\data\public\gc2\production\gc2.xml 1
Download: C:\Program Files\Stardock\SDCentral\temp\gc2.sdc 0 (attempt: 1, HTML code was detected within the download, code: -18)
Download: C:\Program Files\Stardock\SDCentral\temp\gc2.sdc 0 (attempt: 2, HTML code was detected within the download, code: -18)
Download: C:\Program Files\Stardock\SDCentral\temp\gc2.sdc 0 (attempt: 3, HTML code was detected within the download, code: -18)
Result: Installation failed (0)