I see that it is the earliest point in the timeline so would that be a good place to start it? I have 2 and 3.

The timeline doesn't really matter that much, though 3 gives you more impact if you know the story of previous games. I'd say if you go chronologically, you might be pissed of at the gameplay of older games.

Start with 1.

Not as much as you'd think. It's a game that has little relation to the two before it, at least on the surface, but opens you for a few winks and nods that you'll invariably miss without knowing the happenings of the original two. 
 
You should start with the ''story release'' order, beginning with Twin Snakes on the Gamecube most preferably, then switching to Substance on whichever.

Is Twin Snakes preferable over the original?

" Is Twin Snakes preferable over the original? "

Definetly not, man. Just go through in the order they came out. And since story is really why you play Metal Gear, i'd even recommened playing the first one somehow.

Or wait for the HD versions coming in a bundle for PS3...... ;)
 
  http://www.computerandvideogames.com/273641/news/mgs-final-fantasy-hd-collections-coming/

" Or wait for the HD versions coming in a bundle for PS3...... ;)
 
  http://www.computerandvideogames.com/273641/news/mgs-final-fantasy-hd-collections-coming/ "

I wouldn't recommend Twin Snakes, personally.  It is slightly more modern in the gameplay and graphics department, but they really butchered a lot of the dialogue - they went to the effort of brining back most of the original voices actors, but it really sounds like most of them are just phoning it in..  Some of the epic or dramatic lines are ruined.  It was also released in the wake of the Spider-man movies and in several of the cut-scenes they seem to have given Snake over the top acrobatic abilities, which look completely ridiculous.  There's one scene where he literally clings to the wall, directly mimicking one of the scenes from the first Spider-man movie.  Considering he has no acrobatic abilities in later games, it's very jarring.
 
Unless you really struggle with going back and playing a somewhat dated PSOne game, I'd definitely recommend the original over Twin Snakes

" Is Twin Snakes preferable over the original? "

" I wouldn't recommend Twin Snakes, personally.  It is slightly more modern in the gameplay and graphics department, but they really butchered a lot of the dialogue - they went to the effort of brining back most of the original voices actors, but it really sounds like most of them are just phoning it in..  Some of the epic or dramatic lines are ruined.  It was also released in the wake of the Spider-man movies and in several of the cut-scenes they seem to have given Snake over the top acrobatic abilities, which look completely ridiculous.  There's one scene where he literally clings to the wall, directly mimicking one of the scenes from the first Spider-man movie.  Considering he has no acrobatic abilities in later games, it's very jarring. Unless you really struggle with going back and playing a somewhat dated PSOne game, I'd definitely recommend the original over Twin Snakes "

I do love older games.

MGS 3 is my favorite in the series (and it's a prequel) so yes

" MGS 3 is my favorite in the series (and it's a prequel) so yes "

I say start with the first one. This is all based on gameplay. Besides, when it comes to developers making a prequel as the 3rd entry into the series, that's when you know that the 1st or 2nd MGS game won't spoil anything significant for you.

If I had the benefit of having this decision to make I'd play MGS 3 first then MGS and then stop because I just did not enjoy a moment of two and four.

You should play the original MGS. It's still an amazing game and you'll feel terrific going through it. I think you should go with that rather than Twin Snakes. Twin Snakes may be the worst MGS game. I think anyone who says Twin Snakes is better probably didn't play the original first or just didn't play it at all.

Just start with the original MGS1.
 
I played it for the first time last year. I had not trouble with it.

No.  Start with 1 and work your way through the numbers.

I'd say start with 1 and go through like that

There are a lot of winks and nods to previous games in the series that'll be lost on you if you start with 3. Just yeah, go with MGS and work your way up from there.

" Just start with the original MGS1.  I played it for the first time last year. I had not trouble with it. "

MGS1 is still a ton of fun to play. I don't care how dated the gameplay is. Play them in order of release date (1, 2, 3, and 4). I'm not sure where any of the PSP games would fall, but I really enjoyed playing through all the MGS games in order.