SPA400 vs Rhino/Digium card


I’m a new member in VoIP world. I want to implement a VoIP PBX using asterisk in the office but I have one doubt. Which is the best way to use actual PSTN lines in the VoIP PBX? Using a box as Linksys SPA400 or installing a PCI card (Rhino/Digium…) into the server? Which advantages/problems will I have with each option?