Nginx is a great web server to handle tons of traffic with relative low resources, it beats Apache big time.
The problem is that Ubuntu Hardy 8.04 comes with Nginx version 0.5 (version 1.0 has been recently released), and lacks of some features as Cache. An easy way to update the version to a more recent one (currently, to 0.8) without upgrading the whole Ubuntu version is using the following PPA repository: https://launchpad.net/~meto/+archive/nconfig
To add this repository to your system, you need to create a file inside /etc/apt/sources.list.d/ (for instance, nginx-stable.list) with the following content:
deb http://ppa.launchpad.net/meto/nconfig/ubuntu hardy main deb-src http://ppa.launchpad.net/meto/nconfig/ubuntu hardy main
Then, you need to add the key of the repository to your system:
apt-key adv --keyserver keyserver.ubuntu.com --recv-keys ED283389
apt-get update && apt-get upgrade
You should be prompted about a newer version of nginx, say yes, and that’s it, enjoy ;).