Lately I have been spending a lot of time on Linux (FC6 to be precise), and I have notice some visual irregularities with this website while using Firefox on that operating system, especially at higher resolutions.
It is now clear to me that I will need to place more emphasis on testing the user interface of my sites on various operating systems, as well as the usual combinations of web browser and screen resolutions. For the record, I will be aiming at compatibility with the following systems (which I have access to) with future releases:
Ah, the joys of being a UI designer ;-)
Updated 2021 : note that the above post is out-of-date, given this post was originally published in 2007, but is left here for archival purposes.