Photoshop cutting out backgrounds

I have a copy of Photoshop CS2 but this applies to any Photoshop version. I took a photo of a book laid open on a black background and I am trying to clean cut it out but the edge of the book blends (under close magnification) into the black background making it difficult to cut out.

The hardest thing is trying to move the mouse or the pentab diagnolly down the mousepad or pentablet without sudden movements sideways which cut into the image.

Could you please describe the steps I need to take to clean cut this book out and ways to avoid the problem I highlighted (moving the mouse diagnolly (with in this case the erase brush tool).

Thanks
Bruce