I've been spending this winter break getting into new TV shows actually. First one was Fringe, which is on Fox on Tuesday nights. I've never seen the X-Files, but supposedly it's kind of like that. It was created by the creator of LOST. There's only been 10 episodes so far, and I think you could jump in without being too lost. I would watch the Pilot online if you can and that's really enough to be able to follow. Also I think they're showing repeats until it starts up again on the 20th.
Next I'm in the middle of catching up on Survivor which I missed the first few episodes of the past season, so I didn't want to jump in late. I know it's not very popular anymore but you can always watch a new season of that without being lost.
Then there's 24, though I seem to remember you posting in the 24 threads in the past anyways so I'm sure you know about this one.
I saw Snakes mention The Wire (and again since I started typing this) which is what I'm going to watch after Survivor. Downloaded the first season yesterday, and I've heard good things so I'm looking forward to that.