virtualbox.org

I'm running ubuntu 8.04 and virtualbox and want to try out arch linux 2009.02

I mount the .iso at the virtual machine and select to boot arch linux then get the "error" in the following picture

I have tried to redownload the .iso three times from both bittorrent and a mirror

This is generally known as a kernel panic. Either you have some settings that Arch doesn't like, or there is some other problem. See if you can boot the liveCD from Ubuntu in that VM. If you can, then it's more likely an Arch issue. You can also try the latest PUEL version, found on the website here.