Images for several CentOs flavours are available.

1. CentOs 5.1
   Size (compressed/uncompressed): 620 MBytes / 2.53 GBytes
   Link: http://downloads.sourceforge.net/virtualboximage/centos-5.1-x86.7z
   Active user account(s)(username/password): root/roottoor, centos/reverse
   Notes: GNOME desktop environment, Guest Additions not installed.
2. CentOs 5.2
   Size (compressed/uncompressed): 529 MBytes / 2.53 GBytes
   Link: http://downloads.sourceforge.net/virtualboximage/centos-5.2-x86.7z
   Active user account(s)(username/password): root/toortoor
   Notes: NO GUI; Guest Additions not installed; additional server package installed
3. CentOs 5.3
   Size (compressed/uncompressed): 668.1 MBytes / 3.10 GBytes
   Link: http://downloads.sourceforge.net/virtualboximage/centos-5.3-x86.7z
   Active user account(s)(username/password): root/roottoor, centos/reverse
   Notes: GNOME desktop environement; Guest Additions not installed.