To customize your Windows 7 themes you will need some good Windows 7 screensavers. Unfortunately, you can’t really find many good screensavers out there. Anyway, here are some you can use to customize your system.
3D World Screensaver
The Matrix Screensaver
You can download all of the Windows 7 Screensavers here:
Download Windows 7 Screensavers
If you want to download more screensavers for Windows 7, XP and Vista, you should check out the following site:
I’m also working on some more screensavers, but I haven’t found a good converter yet that allows you to convert a gif or an avi file to a screensaver.