1) Guild Wars - NCsoft
2) World Of Warcraft - Vivendi Universal
3) Star Wars Galaxies: The Total Experience - LucasArts
4) The Sims 2 - Electronic Arts
5) The Sims 2 University Expansion Pack - Electronic Arts
6) Half-Life 2 - Vivendi Universal
7) Star Wars: Knights Of The Old Republic 2: The Sith Lords - LucasArts
8) Empire Earth 2 - Vivendi Universal
9) Lego Star Wars - Eidos
10) Stronghold 2 - 2K Games
11) Zoo Tycoon 2 - Microsoft
12) Roller Coaster Tycoon 3 - Atari
13) Sid Meier's Pirates - Atari
14) Rome: Total War - Activision
15) Microsoft Flight Simulator 2004: Century Of Flight - Microsoft
16) The Sims Deluxe - Electronic Arts
17) Warcraft III Battle Chest - Vivendi Universal
18) Star Wars: Knights Of The Old Republic - LucasArts
19) Doom 3 - Activision
20) Sim City 4 Deluxe - Electronic Arts

World of Warcraft sold ~5,000 less copies.

1) Guild Wars - NCsoft
2) World Of Warcraft - Vivendi Universal
3) Empire Earth 2 - Vivendi Universal
4) The Sims 2 - Electronic Arts
5) The Sims 2 University Expansion Pack - Electronic Arts
6) Half-Life 2 - Vivendi Universal
7) Stronghold 2 - 2K Games
8) Guild Wars Collector's Edition - NCsoft
9) Star Wars: Knights Of The Old Republic 2: The Sith Lords - LucasArts
10) Dungeon Lords - DreamCatcher Interactive
11) Lego Star Wars - Eidos
12) Roller Coaster Tycoon 3 - Atari
13) Doom 3 - Activision
14) Rome: Total War - Activision
15) Warcraft III Battle Chest - Vivendi Universal
16) Sid Meier's Pirates! - Atari
17) The Sims Deluxe - Electronic Arts
18) Brothers In Arms: Road To Hill 30 - Ubisoft
19) Zoo Tycoon 2 - Microsoft
20) Microsoft Flight Simulator 2004: Century Of Flight - Microsoft

Guild Wars outsold World of Warcraft by a factor of 2.5.