I am really interested in RPG/FPS now, and I heard so many great things from critics and players alike that Borderlands is awesome. My question is should I play the OG Borderlands and Borderlands 2 before I buy the prequel? Also will it have any effect on the Multiplayer modes online if I buy all three? And what's the multiplayer online like? Is it RPG like?

I've already read lots about the series in Wiki, but I rather ask people who actually played the game!

Play the first one followed by the new one coming out and lastly the 2nd one. That's the order the story takes place so doing that would probably make more sense since the new one is set after 1 but before 2.

I think you're also mistaking the multiplayer for these games since it's pretty much just story campaign but co-op with friends or random drop in players. The game series is fantastic though so have fun.

It's hard to suggest a complete order without having played Pre-sequel yet. However, I would definitely start with the first game. Events in the second game assume you know a bit about the original Vault Hunters and some of the side characters. It's not vital, but I think it helps.

Multi-player is co-op.

Borderlands is about the loot. It's a game where your real goal is to get better weapons. I has an excellent sense of humor, good writing, memorable NPC characters, an awesome setting, and it's a lot of fun to play. The story isn't that strong in the first game but gets much better in the second game, to the point that I'm really interested in what's coming next. Handsome Jack, from the second game (and Pre-sequel) is one of the best video-game characters in recent memory.

Sirens are killer, Commandos are noob friendly.

There isn't much of the traditional RPG about, not like a Fallout type game, other than each class having three skill-trees with different play-styles.

Id say at least play 2 first, if not both. And as said above its online coop. Nice rpg elements, fun shooting, good story split screen coop, and some of the best dlc out there. Also I found most people who play it are helpful and not dickheads.

IMO, game is not really "RPG-like" in terms of multiplayer, but there are RPG elements, excellent shooting mechanics, and stellar story. Some of the best DLC ever. The second one is better than the first but they are both amazing. I would highly recommend playing 1 and 2 before the pre-sequel. The RPG elements really only go as far as skill trees, looting, attributes, enemy and character health displays. That's about it.

The guns are also kind of RPG, especially the secondary modes and the specials, like gun exploding like a grenade on reload. At least I haven't encountered that before.
Oh, and also the gunplay damage/critical modifiers affected by skills. Very RPG IMO.
Yeah, the NPC characters are good and some are extremely funny.

It's a actually a "Pre-Sequel", so it's more or less Borderlands 1.5.
I'd play the original, then the Pre-Sequel (I guess, I haven't played it yet as you can imagine :P) and then 2.
The Multiplayer is basically co-op. there's dueling too, so it's fun as heck with friends!

Sounds good Guys... I will buy it the GOTY Edition for Borderlands 1 when I go to Gamestop manana! Appreciate the advice fellas!!