Baldur's Gate without a doubt!  or planescape though i never played that, supposed to be a good one

Haha, I was thinking that, but I heard it's the longest also!  But also one of the best.  Hmmmm.....

Play the one with the writing talents of Drew Karpyshyn, if you don't know what game I am talking about (you probably don't) it's Baldur's Gate 2.

Play Baldur's Gate 2...and then follow it up with Fallout 1/2.

i'd probably choose planescape after actually... as fallouts take you to a different time in reality, unless you planed on breaking up the gameplay styles a bit

Fallout and then Fallout 2 in preparation for Fallout 3.

If you play BG, BG2, or Torment then find the unofficial patches to bump up the resolution (and to wide screen if you can take advantage of that).  The engine won't feel nearly as dated if you do this.

If you are looking for something that is very easy to get into I would play Diablo first.

All amazing. But you could have gotten the DIablo battle chest. It's cheap and it comes with the original DIablo, DIablo 2 plus expansions, and a strategy guide. I think they still sell them in stores like Best Buy.

Awww sounds killer, id pick Diablo

"All amazing. But you could have gotten the DIablo battle chest. It's cheap and it comes with the original DIablo, DIablo 2 plus expansions, and a strategy guide. I think they still sell them in stores like Best Buy.
"

I would go with Planescape cause for me its the only one I haven't played already.

There's really no wrong order to play them in, so long as you end up playing all of them. 

I haven't played any of them. Where are your classic FPS and RTS games?

My vote is for Fallout. It held my attention better than the rest of those and the combat is absolutely brutal.