Keep your DV137 purely for DVD, as it will play DVD's better than any Blu-Ray player. Also, not every movie is released on Blu-Ray, so chances are you will still buy DVD's for a while yet. Also, do you really want to replace every single DVD you own with a Blu-Ray? I know I certainly don't.
Also, just to add. The first Blu-Ray disc I ever saw was SWAT, played on a Samsung BD-P1000 through an Optoma HD80 on a 3m wide screen. Just after that I tried Blade on DVD from an Arcam DV29, through the same projector on the same screen and I seriously preferred the DVD.
With the right equipment DVD can still look better. I know that shouldn't really be the case, but I have seen it for myself.