Might I suggest a look at the Nikon Coolscan models if this is for semi pro or archival work. I won't bother getting into an optical peeing contest - they're all pretty good.
Check out Nikon for the ICE software it is bundled with - adds time to the scan but I have never, ever seen such incredible results in one step deletion of dirt, dust, scratches and the effects of time on negs and trannies.
Rob