Vista comes with a hidden Bootup Screen which is a little bit prettier than the default one that has a black screen and a progress bar. The hidden looks a bit like the Aurora Borealis.
To change bootup graphic, you access the System Configuration Window by typing "msconfig" in the search box of the Windows Start Menu. Run the utility as an administrator, but if you don't, don't worry. The UAC will prompt to make sure you want to access this window. Once the window is open, go to the Boot tab, check the "No GUI boot" checkbox and then click the OK button.
The next time you restart your computer you will see the prettier bootup screen.
If you still don't like the bootup screen, then you can create your own using a 3rd party utility: Windows Vista Boot Generator.