This is an instructable detailing how to create a keyboard shortcut so that you can quickly switch to screensaver at any time.
Step 1: Creating the Shortcut on the Desktop
Go to the folder C:\Windows\System32 and sort by filetype. Look for the screensaver file type (.scr). Find the file scrnsave.scr (you can choose any of the screensavers, this is the black screen one).
Right click and select send to>desktop (create shortcut).
Step 2: Assigning the Keyboard Shortcut
Right click on the shortcut on the desktop and select properties. Select the shortcut tab and there should be a field named "shortcut key". I chose to use the shortcut "CTRL + ALT + S" but any that isn't already used by windows should be fine.
Step 3: Making the Shortcut Invisible
Now we have a functioning screensaver keyboard shortcut, test it out. However it looks ugly on the desktop, you might be fine with that, but I wasn't so here's how you make it "invisible" (the cheat way).
Right click anywhere on the desktop and select the "view" menu. Un-check the option "Align to Grid" (if it's un-checked, leave it). Drag the icon to any of the edges of your screen until you can't see any of the text/image. Mine's in the top right so I won't accidentally click it.
You're done! Use it wisely, it can be a powerful tool!