Yeah, and originally, Ross was actually going to play Dave, himself, but FOX thought he looked too old (his hair IS just a little gray from what I've seen), so they went through several different people who they approached to play Dave until Jason Lee finally accepted, mainly because he found out they approached Bill Murray as well and he turned it down, as apparently Murray is one of Lee's biggest influences.
What I don't understand is why they approached Bill Murray, Tim Allen, and John Travolta (to name a few) to play Dave... aren't they all a little "too old" to play him as well?