The Pass cards are plenty, especially if you get them all down (and they include the boxed memory items, so that's another thing you won't have to worry about). I wouldn't worry about the flows until you get there.
If you want to have a few kicks while you learn something, go get Microsoft Flight Sim 2002--it has a reasonable 737 in it. Then go check out
www.dreamfleet2000.com where you can download an add-on 737 (It's a -400, but it's close enough). It includes an MCP and FMC that are accurate enough that you can teach yourself (it has a tutorial) how to run it, and most of the overhead and console panels so you can practice the flows, etc.
Beats reading a dry old manual, and you can buzz the casinos in Las Vegas and practice getting slam dunked by ATC
If you want some more study material, you can check out
www.canovair.com for their cockpit guides. Covers the -200 and -300/500 (not sure if he has a -700 yet).
But to echo what's been said above, if you do what they tell you to do after you get to school, they will get you through the program. Spend "some" time preparing yourself beforehand, but don't devote your life to it or anything. Spend the "quality time" with your family and friends, because you won't get a whole lot of it for several months after you start...