Thanks for the link. However, that piece is outdated, despite being written this past summer. The author installed the HVR-1800 on Ubuntu 7.10, which uses the 2.6.22 kernel. I've read enough to know that 2.6.24 supports the HVR-1800. I confirmed the kernel module is installed in my Slackware 12.1 (22.214.171.124) kernel configuration.
Generally, I have found reports that the digital reception is supported but not the analog, but with the upcoming coerced switchover in February, I'm not overly concerned about analog. Yet because MythTV is an add-on effort within Slackware, I'm seeking opinions from slackers using that card under 12.1. I've got a good handle on the research, I merely want to read opinions from a few slackers because that is the OS I use.