Here are some useful registry keys for Windows 7 Aero Peek. If you don't know how to edit the registry, you probably shouldn't be messing with it.
These are all 32-bit DWORDs.
* DesktopLivePreviewHoverTime - 0
- Time between mousing over the bottom right and the desktop appearing
* ThumbnailLivePreviewHoverTime - 4294967295 or 3600000
- time between hovering over the taskbar thumbnail and the preview showing
* ExtendedUIHoverTime - 0
- time between hovering over the taskbar item and the thumbnails showing
- Alt-tab live preview delay time
DWORD max value 4294967295
Log out, log back in, and you're good to go.