While I haven't read The Hammer and the Cross, reading about it reminds me of a series that I haven't read myself but which my roommate recommended very highly, Bernard Cornwell's Saxon Chronicles, beginning with
The Last Kingdom. While these books aren't alternate history SF, they're well regarded historical fiction, so that might scratch your viking itch.
A couple of medieval SF books also come to mind.
The High Crusade by Poul Anderson takes place a bit later, in the 14th century, but is tremendously entertaining. It's about aliens versus knights and is a helluva lot of fun. In a more serious vein,
Doomsday Book by Connie Willis is about a historian in a future where time travel is used for research. She gets sent to 14th century England, but her timing is off and she winds up smack in the middle of the Black Plague. Things get complicated from there. Doomsday Book won both the Hugo and the Nebula, so that's probably a good sign that you'd enjoy it.
As for Anno Dracula, have you read the sequels
The Bloody Red Baron and
Judgment of Tears: Anno Dracula 1959 (aka
Dracula Cha Cha Cha)? If so, while no alternate history horror stories come immediately to mind, perhaps you'd enjoy Tim Power's supernatural secret histories? Check out
The Anubis Gates which is about time travel, Egyptian cultists, werewolves, beggar gangs, and Samuel Taylor Coleridge. It kicks ass.
FnordChan