Its Spartacus: Blood and Sand followed by Spartacus: Gods of the Arena.
Spartacus Season 2 is premiering on January 27th, so get to watching it now!
Overall, its in my top 3 TV shows of all time with Battlestar Galactica and Terminator: The Sarah Connor Chronicles. Another poster said its 30% sex and 70% violence, and that is probably about right in terms of X-rated content (the sex almost invariably has a reason for existing in the show - either to show the debauchery of the time period, or to further a plot point). But its 100% story and character development. Absolutely phenomenal series. John Hannah (Battiatus) gives one of the best performances in TV history, IMO. And his father Titus (Jeffrey Thomas) may be even better in Gods of the arena.
There is so much deception, backstabbing, and one-upmanship in the show, its great. Both season ending episodes are right up there with the 5 best TV episodes I've ever seen in my life. Starz did an incredible job with the series, there's a reason they renewed it before the first episode even aired.
Its not a show for kids. You absolutely must be 18+ to watch it. It doesn't go as far as to show cock-n-balls, but its just a step down from it. The foul language is hilarious, and they constantly come up with new phrases that are unmatched in hilarity (http://www.youtube.com/watch?v=ruyWq7URlN0).
Overall, its the best series still on TV by a country mile. Nothing is close. Since we know the historicity of the source text, I don't see how they are going to wind up with a massive failure at the end like BSG was, so I'm very excited about where it goes.
As others have said, the first two or three episodes are kind of slow, as they introduce all the main characters (Sparatcus: Blood and Sand, mind you). Once thats over with, the rest of the series is sheer brilliance. There should be enough killing, boobs and vagina in the first three episodes to keep you satiated until the plot thickens, though.
Dang it, I'm gonna go watch it again right now to get revved up for Vengeance.
Back from the dead, I'm afraid.
