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.
![Posted Image](http://cache.gawker.com/assets/images/lifehacker/2009/03/Win7LogonThemes1.png)
Read On to accomplish this magical feat...