Just a note: if you don't have a high definition TV, don't bother with Blu-Ray. This is especially true if you want to watch Star Trek or other "full screen" TV series. The picture will not fill the screen and be quite smaller, because the format is made to fit the 16:9 widescreen aspect ratio. Widescreen movies will always have the black bars and the top and bottom, which probably won't be an issue, but Star Trek is in 4:3 and it will have the black bars on the top and bottom as well as
the side. It's in the same space as a widescreen movie, but inhabits only the center of the screen. This makes the picture a good 30% smaller, I would guess. Also, the picture quality of DVD is still excellent in standard def, so there's no reason to convert if the equipment you have is working fine. If your set breaks, there are plenty of working models at thrift stores, Goodwill, Craig's List and garage sales for very little money.
My HDTV crapped out last year and I haven't been able to replace it yet (the cheapest is still more than I can spend before fixing a car and my fence). Thankfully I still had an old, trusty tube set. Also luckily, I never got rid of my Trek DVDs after I got the Blu-Rays because standard def fills the screen.
As for which versions to choose, I'd go for the original effects if you're used to them after all this time. If you're anything like me, you'll find the new effects interesting and enjoyable (some even help the stories), but you'll prefer what you always had. If all you can swing is one, get the one you KNOW you'll enjoy.