Step 1
Navigate to the folder Windows\Resources\Themes. Either drag and drop the "Aero Theme" file to your desktop, or right-click the file and select "Copy," then right click your Desktop and select "Paste." You'll need to edit the file from the Desktop since Windows has it write-protected in the Themes folder.
Step 2
Right-click the Aero Theme and select "Open with," then select Notepad. Scroll down all the way to the bottom of the file. Insert the following text, including the URL of the RSS feed after the final "=" symbol: [Slideshow] Interval=1800000 Shuffle=1 RssFeed=
Step 3
Save the file by clicking "File," then "Save" in the top Notepad menu. If you don't have a Windows Live login, either create one on Windows' site or skip the option to format with FrameIt.
Step 4
Format the feed to fit your screen by going to FrameIt's site (see Resources) and signing in via your Windows Live login information. Click "Custom" and add the full URL of your RSS feed; it will be formatted automatically. Customize it if necessary by clicking on "Manage Settings" and selecting a different screen size. Click "Set up a frame" to create a link, then copy and paste that link after the equals sign at the end of the Aero Theme file. Save the file.
Step 5
Activate the Aero Theme by double-clicking it. When prompted, chose to save locally. Wait for the RSS feed to download, and within a minute or so, depending on your Internet connection, you'll have the RSS feed on your background.