Surviving the Front Page of HN for Noobs
blog.hartleybrody.com
blog.hartleybrody.com
I think you should probably look into the configuration of your server, rather than throwing more hardware at the problem.
I made a few tweaks, but it was pretty vanilla. I also used Amazon's CloudFront to host my gzipped CSS/JS.
Did you have something like WPSuperCache installed? That can help a lot by pre-caching all your pages into static html.
1. I spent all day dealing with it, so it seemed significant at least to me
2. Most of the sites that make the front page are large hosted sites with a dedicated IT team, so the case of a small site making it seemed like a somewhat interesting hosting challenge