Tropico 3 is my first exposure to the Tropico series and am loving it. Despite picking it up for XBox, I'm not averse to a bit of PC gaming.

Is it worth me picking up the originals? Will I get anything out of them or will I just be playing a downgrade? From what I can see the gameplay looks very similar??

Pirate Cove is a totally different game with a totally different dynamic. I liked it, but I'm probably in a minority there.

Similar graphics, and broadly similar gameplay, but rather than managing Tropicans, you manage two types of people: pirates and slaves. Both classes have specific needs and interests and there's a ton of micromanaging, especially your pirates. It's also a much more landscape-focused game: some structures and decorations produce Anarchy, for example, which pirates like but makes slaves inclined to try and run away; others produce Fear, which helps keeps slaves in line but annoys pirates. Balancing these is probably the meat of the game.

Tropico 1 is Tropico 3 in 2D. The edicts, buildings, gameplay and even the text are all substantially the same. I think that T1 has better scenarios, but T3 has a better sandbox mode and is a more "complete" game on the whole. (Features like garages are totally absent from T1.)

The first Tropico was outstanding. I highly recommend it, although, as Snuggles said, it was very similar to Tropico 3. The elections seemed a bit more of a challenge in the first one, but maybe that's just me. I liked the old graffiti-covered building models better; YMMV.

The second Tropico was an okay game that with some hacking became a lot of fun. Check out the old Cafe Tropico forum for lots of insight from the developers themselves on how to edit the code if you're into that sort of thing. Absolutely the most support for modding that I've ever seen from any game that wasn't opensource.

I liked Tropico 2 the most because who doesn't like to control a pirate island? Tropico 3 is the true sequel to Tropico (the original).