Although probably not the best way to block MSN ads, I discovered this method accidentally while debugging my PHP app. Here’s what you do:

• Download and install Fiddler
• Run Fiddler and launch MSN live
• Watch the web sessions window in fiddler until you see something like “ads1.msn.com” in the hosts column - this might be different for other PC’s, I’m not sure
• Add this line to your “C:\WINDOWS\system32\drivers\etc\hosts” file:
• 127.0.0.1    ads1.msn.com

This redirects any requests to the ad server to your localhost. A minor drawback is the annoying popup messages you get when it fails to connect, but it works No more ads!

I’m sure with a little more inspiration and time you could hack it to serve up whatever image you want, your very own MSN skinner! Enjoy