I agree, if SSE2 makes a major difference, then fantastic we should do it, but there are plenty of reliable older boxes around so its tough to wipe them all out for the sake of a few more calls per box.
A great option would be for SSE(PIII+) or SSE2(P4+) to be admin selectable in preferences, This way upgrading an older server to a newer platform would be pretty painless. With the default being SSE for compatibility.
Testing build 3430 now, thank you!
Cheers,
Marcus.