My vote for the PVR-150.
ONE CAUTION - I read somewhere that Hauppage is shipping a newer card in the PVR-150 boxes; this card is _not_ supported by a linux driver. You should research this before buying.
I don't know what distribution you're using (or planning to use) but as of Ubuntu 7.04 (Feisty), the PVR-150 and Myth are literally Plug-N-Play. The 150 is automatically detected, installed, and live with the initial install (no setup required, not even installing the drivers from the repository). MythTV works immediately after installing from the repository (and rebooting).
This is a huge step from the prior version (6.10 Edgy) where I spent weeks trying to set up a DVR.
The LIRC package in Ubuntu is easy to set up (minimal command line usage) and supports many remotes including the Hauppage one that comes with the PVR-150, and the X-10 / ATI Remote Wonder (which I have).
Of course, gov_coders post makes me want to get an HD tuner now