Vanguard wants you to come home for the holidays and spend an evening next to your fireplace in Telon. In conjunction with their holiday events, former subscribers that were inactive for longer than 45 days have had their accounts reactivated until January 31st, 2009. You don't have to do anything to pick up the free game time, all you need to do is run Vanguard and play. Even if you don't have your disks, you can still download the trial client and it will patch you up to the full client when you run it.
The free game time will let you check out the new features to the game, like the addition of fishing, a new ship, a new raid, new enhancement slots, the Festival of Gloriann and all the decorations that come with it. So fly back to Telon with Randolph the Flying Reindeer and fight off some evil snowmen. It's free!