I was wondering if A) all of the books are in the game at all and if so then B) where are they to be found.

Frostfall I found in the Chapel of Diebella in Anvil. Second Seed I errr. . . checked out from The Elder Scrolls Library in White Gold Tower. I am hoping to track down the others, if they exist within the game. Help me if you can.

Are they genuine historical accounts of Tamrielic events, by the way?

They're all in the game (as near as I can tell at least) but most of them are skill books and are unique or at best quite rare. They're scattered all over the place.

http://www.uesp.net/wiki/Oblivion:Books is a list of all the books in the game, including the 2920 books, and their locations. Obviously it's a bit of a spoiler.....

They're nominally real history, but since they concern the history of Vivec and the Tribunal, they should definitely be taken with a grain of salt.

I was going to start a new thread but I saw this one for my question. Whats the rarest book in the game?

There are two non quest related books that can only be found in one place each:

Remanada - You can find one copy in the east wing of Cloud Ruler Temple. You won't find it anywhere else.

Hiding with the Shadow - You can find it in Lake Arrius Caverns.

Those are the rarest that I know of.

Thanks So much Gpstr. I have kinda started a selfmade quest for my Archmage to get a hold to the complete set of these rare books. I have run across some other good ones in my wanderings, btw. Love the lore. Looking forward to new discoveries in Skyrim. Thanks a lot for your answers and input.