Unless you intend to rent/purchase Blu-Ray movies (HD-DVD is dead), there's no reason to get a player. My standard DVDs look just fine on my HDTV.
I can't speak to any particular brand or model of Blu-Ray players, but I know a lot of people just use their PS3 for Blu-Ray movies. Some others have opted to add a Blu-Ray drive to their Home Theater PC, which is the way I'm leaning if I ever get an HD projector.
My personal suggestion would be to not get anything until you think your current DVD player just doesn't hack it anymore.
Some movies if watched at hi-def would look like a TV programs, everything is cleaner and high detail like the one recorded in video cam, but it eliminate the fun of watching it like in the theatre. Some movies like the Transformers on the other hand makes it pleasing to watch in hi-def. I think it’s something to do with the filters used when they make some scene, so standard definition is better on some movies.
Also some TV will convert standard definition to hi-definition; something you need to check about your tv.