I'd add a vote for a GOG release also - at least use it for a minimum-cost patch for existing DD owners. Please *don't* restrict it to Steam or any other service using online activation since these systems can leave purchasers in the lurch if they shut down (or worse, impose a maintenance fee to keep accounts open).
As for changes, fix the outstanding bugs (the sight range bug mentioned by Raze above is one I particularly remember ) and flesh out the Wastelands more (perhaps even provide a way to return to Rivellon for some new quests).
And please remove the disk check as well - legitimate purchasers shouldn't have to rely on third parties for this.