Happy travels in your Voip adventure. After six years here is where I've ended up:

A good ATA obihia
A good IP phone Aastra 6700 series
A good PBX distro (Freepbx + Astrisk) pbxinaflash

Recommend sites:
VOIP Tech Chat
pbxinflash
Nerdvittles

Voipo keeps the wife happy connected to the house wiring with a good ATA and DECT 6.0 cordless. A good playground with pseduo pbx features is voip.ms