I agree with John, you may want to stop trying to put the book on the scanner and instead put the scanner on the book. My Dad had an Amiga that he used for his music. I haven't unpacked it yet, and who knows what I'm going to find when I do. But a friend of his tells me that the Amiga was perfectly suited to music (though at this point in time and the age of that computer, I don't know what to tell you about saving data, speed, etc.). One of the things included in the box of stuff is a hand-held scanner. He spent a lot of time mulling over this (as a retired reference librarian, he's the last one you'd find mashing a book spine with a scanner cover).
And for something completely different, you might want to look around and see what agencies or entities have big fancy scanners and figure out if you can work out something. Here at the Special Collections at my university we have a big scanner--an Agfa Duoscan T2000 XL that scans up to 4000dpi. It has a cover on a special expanding hinge that will allow for very thick volumes to be scanned. At the highest rate, a postage stamp might be scanned and would completely fill a CD. You probably only need to scan at 300dpi at the highest. With this Agfa scanner and Photoshop, you can get the kind of image that your other software can interpret. So perhaps you need to find someplace that will let you work out a deal. Volunteer to do scanning for a local library or museum, in exchange for some time scanning your own stuff. spend your money on high-end software instead of trying to buy the new scanner AND the software.
Before you give up on the scanner and computer combination that you already have, visit the web site for the scanner manufacturer and download any upgrades they have made available for your machines. HP (as an example) has an excellent site for upgrading software to support its machines. I've gone in to get bits and pieces for various peripherals for my computer on several occasions.