There are many other tutorials out there on how to install fonts in Windows 7, but all those I've seen take for granted all their readers know exactly what to touch and what not in their hard disk's Windows folder; since I tend not to assume anything, here's a font installation tutorials pretty much for dummies (the ones utterly scared of entering their C: folder).
This method is particularly useful to install several fonts at the same time, and it cuts time, too: it starts with a visit to any free fonts archive; the best and biggest ones are DaFont and Urban-Fonts, but this tutorial is valid for any website offering downloadble free fonts - once you've downloaded a font, the process to add it to your Windows fonts is the same.
First of all, of course, pick and download the font you like; for this tutorial, I chose a font called Violet, but you can do this with how many fonts you want to install (sometimes, I do this with like 5-6 fonts in a row).
Download the *zip file wherever you like; once you did it, unzip it. *To do that, you'll need a program like Winzip - the one I use - or Winrar; I suggest the second (the trial never ends, despite being shareware, just close the purchase-ad pop-up and you're set) or, if you want freeware programs, there are both 7-zip or jZip.*
Once the file is unzipped, you'll see something like the image down here.
The one you want is the left one; that is your font.
Now click with the mouse's right-button to see the menu below, and select either the Crop (or the Copy below) command.
Once it's done, file should look like this.
Now, select your hard-disc from your windows' left menu and, on your left, you should see a folder called Windows, like shown in the image down here.
Enter it, search for a folder called Fonts identified by a big, blue capital A (the pink square on the image left) and click it.
Welcome to your computer's fonts. :) Now, all you've left to do is click with the mouse's right button and select the Paste command. A tab will appear, saying like "the selected fonts are being installed"; when that tab disappears...you're done!!!
The selected fonts have been installed and can now be used on any program - Microsoft Office, OpenOffice, Adobe Photoshop and Dreamweaver, etc.; enjoy your new fonts! ^.^