Xeon 5050's in a Skulltrail

I broke down and bought a Skulltrail mobo to use with my Xeon 5050's but I am starting to be concerned that they might not work because they are 667 FSB and SkullTrail handles 1066-1600 FSB.

Is this a Problem?

The bus isn't really 1066, or 1600. I'd love to say otherwise, but big numbers wow people, and thus marketing exploits people with big numbers. Think Double Data Rate (DDR) in addition to multiple cpus or cores - now we're talking Quad Data Rate (QDR).
"Skulltrail has a front side bus rate of 400 MHz (1600 MHz QDR), " - http://en.wikipedia.org/wiki/Intel_SkullTrail

Likewise, your CPU FBS' aren't really 667MHz.. they are actually 333MHz with data sent on both the upswing and downswing of a square wave. Thus, Double Data Rate. There shouldn't be a problem as a marketing-enabled FSB of 1066 is really only running at 266MHz, and a 1600 FSB is really 400MHz.