Fro information on how to change the screen savers, go look at the link below.  I found this info on the Windows Vista Magazine blog - http://www.windowsvistamagazine.co.uk/page/windows... 

The sad sad fact is Windows Vista will be shipping with screensavers without the options to be configured, however they were originally designed to be customizable. Stephen Coy tells me this feature might be available after Vista ships, perhaps in a powertoy or service pack? But if you can’t wait, then you can follow the steps below to customize the screensavers through the registry.

Source: Registry hacks for the Windows Vista screensavers at istartedsomething