Hmmm.. the link is working for me, here is what it says:
3DMark Cow History:
• In 2001 you can enable an easteregg where you can drive around and shoot down flying cows:
Open the Edit Projekt dialog and insert Holy Cow! as Project Name, this will unlock the Game Demo button.
• In 03 there are some cows at the end of the first part of the demo.
• In 05 you can enable an easteregg that replaces some of the the Arolphins (flying dolphins) with Cowlfins (flying cows) at the end of the Demo (credits screen):
Start 3DMark05 with the commandline parameter -lehmä and run the demo.
"C:\Program Files\Futuremark\3DMark05\3DMark05.exe" -lehmä