netdevil - if you want to play with Asterisk, you can always use a softphone as well. I think CounterPath still makes a free softphone called X-Lite. There are a couple other freeware softphones as well, SJPhone comes to mind. I build Asterisk on Fedora.
For PVR I actually use a pair of Windows solutions: SnapStream's BeyondTV for recording and TVersity for UPNP streaming. BeyondTV is licensed, TVersity is free. On linux there is MythTV. I tinkered with it years ago and it looked interesting but was still a bit unbaked. I imagine it is far better now.
I may break down any try tinkering one last time with DNS Relay, SIP ALG, etc. We have visitors frequently enough that the guest zone is very handy. My wife started getting very irritated with the phone service instability, so if I do start fiddling with the DIR 655 settings again, I'll watch it like a hawk.