Quite simple:
The requested URL /admin/ was not found on this server.
error.log says:
[Fri Sep 7 18:45:12 2007] [error] [client 69.157.231.51] File does not exist: /var/www/admin/
oxfamqc:/etc/apache# ls -la
total 56
drwxr-xr-x 3 root root 4096 Sep 7 18:38 .
drwxr-xr-x 60 root root 4096 Sep 7 18:39 ..
-rw-r--r-- 1 root root 285 Sep 7 18:37 access.conf
drwxr-xr-x 2 root root 4096 Sep 7 18:38 conf.d
-rw-r--r-- 1 root root 35457 Sep 7 18:37 httpd.conf
lrwxrwxrwx 1 root root 15 Sep 7 18:37 mime.types -> /etc/mime.types
-rw-r--r-- 1 root root 297 Sep 7 18:37 srm.conf
oxfamqc:/etc/apache# ls -la conf.d/
total 12
drwxr-xr-x 2 root root 4096 Sep 7 18:38 .
drwxr-xr-x 3 root root 4096 Sep 7 18:38 ..
lrwxrwxrwx 1 root root 24 Sep 7 18:38 alternc.conf -> /etc/alternc/apache.conf
lrwxrwxrwx 1 root root 41 Sep 7 18:38 override_php.conf -> /var/alternc/apacheconf/override_php.conf
-rw-r--r-- 1 root root 133 Jul 2 20:43 php5.conf