Darn, Arris beat me to it, I was going to say reduce the size of your signature, but Arris already did
I believe this is a per-user setting which can be changed in the registry in HKEY_USERS\S-1-5-XX-XXXXXXXXXX-XXXXXXXXXX-XXXXXXXXXX-XXX\Control Panel\Cursors
. If no user is logged in yet it loads the settings from HKEY_USERS\.DEFAULT
where you can also change the cursor scheme in HKEY_USERS\.DEFAULT\Control Panel\Cursors
. If you Export that key from a user which uses the Aero cursors, open the exported .reg file in notepad, find/replace S-1-5-XX-XXXXXXXXXX-XXXXXXXXXX-XXXXXXXXXX-XXX
and import it you 'll get the Aero cursors at logon screen.