The season premiere of LOST is on Tuesday February 2, 2010.
It starts at 8PM EST on ABC.
I'm not saying this as a fanatic, I don't have posters or action figures ... I don't even own any of the DVDs from previous seasons ... this is just one of the most compelling stories ever told.
I'd strongly encourage you to watch.
If you'd like to catch up ... you can probably get seasons 1-4 on DVD from your local library. I rented season 5 from Blockbuster.
You can also watch and catch up on ABC.COM and on iTunes.
The SYFY Network and G4 also rerun previous seasons.