Digital Media player for audio books - any advice welcomed

I am looking for a media player suitable for use for playing audio books. I have 100's of hours of ab and plays on cd, tape and also on my pc. Burning to cd is slow and storage of the cd's is starting to get a bit unwieldy. This is especially as i prefer the unabridged versions of books.

I am not too worried about the size or weight of the player as 99% of the time i will be using it at home (I am an insomniac and use audio books when i cant sleep). I run my current walkman through mini speakers next to the bed and would like to do the same with the media player. If possible i would like a player that can run straight from the (uk) power supply, i will only need the battery on the odd occasions that i go away.

I would also like to put my music cds on the player as well - but the player will be used for audio books nearly all of the time.

I am not too worried about video, pictures, radio or any other bells and whistles.

I have software to split the files so exact bookmarking is not a problem.

I would be interested to hear others experience of the best format for audio books - mp3, ogg, aa etc as this greatly dictates the player purchased. There is loads of information about these formats online but i haven't found much that specifically mentions audio books. If possible i would like to make an informed choice! I've read loads of reviews and am now into information overload and would like a bit of practical advice.

I have ordered the iriver h10 (20gb) from Amazon, but they have a 2 week delay, so i can cancel the order if need be.
Thanks