Dual Core S939, AM2 or - ugh - Core 2 Duo?

Hi, I'm planning to upgrade my 3200+ system to a dual core CPU, either S939 on my existing board which runs fine, AM2 (which would require changing mobo, memory and graphics card) or a Core 2 Duo (same). Any pros or cons from a Linux standpoint? I know the usual hardware reviews like tomshardware or Anandtech but they say little about Linux. Any while we're at it, which AM2 or 775 board has a usable SPDIF input? I would like to spare my sound card ... checked all the usual suspects here as well but no luck. -- Tax reform means "Don't tax you, don't tax me, tax that fellow behind the tree." -- Russell Long