Good luck convincing other people about your msn preference. This forum and other seo forums are typically heavily pro-Google. Even though I dislike Google as a company, their search engine is better than both MSN and Yahoo. Their market dominance reflects this.
I get most of my traffic from Google (this includes all sources, not just search engines). However, Yahoo does send about 15% of my site's traffic so I'm happy with it too. All the rest of the search engines (MSN, Live, AOL, Ask, etc.) only send about 3% of total traffic combined.
This is based on the traffic I received on my sites from search engines. No doubt the big G rules when it comes to organic traffic 1. Big G 2. Yahoo! 3. MSN/ Live