Yet another small but fantastic difference in Windows 7 is that users can finally swap out that drab background used for logon.
The customization still hasn't been designed for the mainstream consumer—probably intended for OEMs like Dell, you'll need to poke around a bit with regedit to change the background screen (full tutorial here). But compared to downloading/installing an entire separate program just to manage this one tiny function (as is necessary with XP and Vista), we'll take it.