Windows 7 Logon Reworked is a sexy welcome screen replacement
If that's how you roll, take a look at Windows 7 Logon Reworked. It's available in three variations -- the one you see above, another with the Windows logo embedded in the login box's glass border, and one more which is completely logo-free. As with a lot of other shell modifications, installing Reworked requires a little bit of tinkering in your system folder. You'll have to replace the stock Windows authui.dll in Safe Mode to do it -- check the author's instructions on DeviantArt if you need help and make sure you create a backup before making any changes!
Both 32 and 64-bit versions are available for all three styles, and there's also a snazzy Aurora-inspired replacement background should you want to change that as well!