Get to watching then, Khilia ;) You can start in Season 5 if you want the juicy parts off the bat. Somebody might hit me for saying this. But I think if you're not half-in love with David Tennant after seeing pictures of the tenth Doctor, I think you'll enjoy Eleven's run more and then you can go back and see S1-S4 to broaden your DW knowledge and get all the fantastic Nine/Ten adventures that have become classic by now.
Or maybe you want to watch Blink or Silence In the Library first... Hmmm. Yeah, if someone doesn't fancy Tennant but want to watch DW, you should start with the episode from S3 called Blink. Then the S4 episodes Silence In The Library and Forest Of The Dead. Then jump to Season 5 :3
What's that, you say? We're not in the DW fanclub? Oops.