It sounds like your graphics card driver doesn't include support for OpenGL acceleration.
I think it's likely that ATI would offer a driver with OpenGL acceleration, could you check their web site for the most recently released version?
http://ati.amd.com/support/driver.htmlThere's a driver dated 16/1/2008, which should contain OpenGL support, whether you're running XP (or older) or Vista. You should only require the 'Display Driver' download rather than the 'Catalyst Software Suite' one (which just contains some optional extras in addition to the display driver, but which should also work fine, if you want the extras).
If this doesn't fix the problem then let me know and I'll ensure it does get fixed. Apologies for not replying sooner, but I don't check the forum very often - if you want to contact me regarding support, then it's best to email me via the 'Contact' link on the main Armadillo Run web page.