As some of you know, for the last five years I have chosen to follow the simple biblical calendar put forth in Torah as opposed to the more popular rabbinic calendar.
Rather than write an article on this, I would rather refer readers to some sites which already have interesting and biblical-based information on the true calendar of G-d. Now, usually the biblical calendar is fairly close to the rabbinical calendar, but in 2005, the rabbinical calendar has added in an extra month (making this a leap year) which causes Passover to fall a month later than the biblical calendar would allow. This means all moedim this coming year will be observed a month later for those following the rabbinic calendar.
Some interesting links about the biblical calendar are:
Karaite Calendar explanation on Abib
Truth On The Web Calendar Chronicles
Also, an interesting Torah-based (non-rabbinic) Haggadah may be found at:
(free download in Adobe format)
Links: Biblical vs Rabbinic Calendar