You need anydvd hd to break the copy protection, a ripping tool (the company that makes anydvd may have a ripper as well), a bluray authoring program, and a bluray burner to burn the authored disc.
Now, it comes down to time and money, is it worth it to you?
Warner bros has a red2blu program for exchanging select wb movies in hd-DVD to bluray for a small fee and shipping and handling. Sometimes it's just cheaper to buy a bluray copy from Amazon or Walmart than paying to swap.
I paid to swap out Planet Earth for $21 with the wb program since it was cost effective at the time.
You still keep the hd-DVD, just send the cover art in.