Well, in case you didn't already know, Windows 7 makes it easier than ever to change your log-on screen and, quite frankly, the 7057 log-on screen is ugly (well it's alright, but I don't like it). So here I've made a log-on screen for myself and I decided to share it.
To change your log-on wallpaper--without messy hacks--in Windows 7 (build 7000 and on) you can use this convenient application: [link]
This is a synthesis of two wallpapers, the official Windows 7 wallpaper and a log-on screen made by Gotier (I think). If Gotier has a problem with me using it this way I encourage him to tell me so and I will remove the image.
Personally, I think it fits the Windows 7 theme very nicely. The quality of the image is low simply because the file size must be small for the logon. But it's high enough to look good in most cases.
Feel free to use this image however you see fit--although Gotier may want attribution.