In the past, Dell would distribute workstations with a Windows OS or no OS. Today, Linux users have the option of ordering a system with Red Hat Enterprise Linux WS, with support, as seen
here.
The RHEL WS provided comes with 2.6.9 Linux kernel, the OpenOffice.org office suite, the Firefox Web browser, several email clients, including Evolution, and the GNOME desktop installed, but the option of KDE available.
While these may not be the best machines available, I still think this is a great step forward for Linux in general. A lot of people that would otherwise try or use Linux have been put off by the fact that they would need to do the installation process on their own. The installation process for Linux isn't always easy, as it can sometimes be difficult to get it to support certain hardware.
I look forward to the day when we'll have the option of other distros at several different companies. I hope that Dell really will succeed at setting a new trend in computer distribution.