From: Ol' Blighty
If you own all three I'd say there is little point in playing the old versions, except perhaps for nostalgia.
However, if you do not own any Distant Worlds games at all, then yes, it certainly is worth buying and playing the old ones. Buying all three in one go as has been discussed endlessly around here is rather expensive. But the original, and the first expansion are both fantastic and unless you have actually played Legends then you won't be aware of what you are missing.
So if starting out, I could very much recommend perhaps DW, 3 months later buy RotS, 3 months later buy Legends. I had countless hours of fun in the old versions, even though I wouldn't go back to them now. The series has got better as it goes along.
Also, my game has been completely stable since the final patch for the original, don't worry, original DW, RotS and Legends are all in very stable states if you keep them patched.
< Message edited by WoodMan -- 3/1/2012 1:41:00 PM >
"My body may be confined to this chair, but my mind is free to explore the universe" - Stephen Hawking