Upgrading my account

Ive got the original Guildwars and I liked it, I play WoW but Im sick of it and Im thinking about upgrading my guildwars account with Factions and or Nightfall. Since I havnt played for a while Im wondering if its worth it to buy both or just the newer of the two.

i would suggest getting Nightfall...then Eye of the North...then go back and hit factions if you still like it. Nightfall introduces hero's and they rock for the most part...Eye of the North...will be where everyone is in late august...just be sure to add them to your existing account rather than making a new account.