I posted this in another thread, but I have had much success running colinux with netatalk to to enable an AFP target on my EX-490 running WHS v1. I began to have issues with the HP TM solution as of 10.6.8, with the backup becoming corrupted every couple of days. I really wanted to upgrade to Lion but had to hold off until I had a working AFP solution.
Since implementing the colinux solution, I have had no issues at all with TM, and have upgraded to Lion without a hitch.
I'm reposting this from wegotserved. The process looks complicated, but the OP there really made this pretty simple from my point of view:http://forum.wegotserved.com/index.php/ ... -netatalk/
While it looks like my CPU usage is high during a TM backup, I've still been able to stream full BD isos at the same time, so performance impact for my use case on a celeron CPU is negligible.