You want to know what has changed in the setting?
Well, in terms of storyline/metaplot, here were the big things. 1372 is the current year the Campaign setting and Players Guide to Faerun are written for (the novels are at 1373 I think).
A Netherese flying city that escaped the Fall of Netheril has returned from planar exile on the Plane of Shadow to hover above Anauroch and they are trying to rebuild the Netherese empire (a shadow-tainted version at that).
The Red Wizards of Thay have generally given up on military conquest of the world, and have decided to go for economic dominance. They use their large numbers of low-level apprentice to churn out bulk magic items for sale, relatively cheap, at diplomatic consulates/enclaves throughout Faerun. This is much of the in-game explanation for the easy magic-item economy of 3rd Edition.
King Azoun IV of Cormyr is dead, killed in battle and Cormyrian law about succession and the way he sacrificed his life made Ressurecting him impossible. There is an infant Azoun V, with Cormyr ruled in his stead by the Regent, Princess Alusair. Cormyr borders on civil war as various noble houses and political factions all vie to manipulate the Princess and possibly steal the throne.
Bane is back. Ixachu Xvim was destroyed as part of Bane's reincarnation/ressurection.
To run it in 3.5, get the Forgotten Realms Campaign Setting (the best single-book Campaign setting I've seen done), and the Players Guide to Faerun (the 3.5 update of the material in the Campaign setting, and some more storyline/metaplot info, and miscellaneous stuff like Elven High Magic). Next personally I'd recommend Magic of Faerun and maybe Monsters of Faerun (a lot of setting-specific creatures like the Phaerimm and Sharn are only here). Virtually all the setting material can be used as-is, with whatever mechanical changes overcome by a resourceful DM.