Well, first of all you can disable/uninstall all of the "crap"ware. If you're still convenced, then disable more things.
To start from the begining:
When you pop your vista disk into the computer to reinstall one of the first steps will be to "choose your partition you want to install Windows Vista on". From there it shows all of the partitions. You go over them, and you can delete all of them, creating one big partition, 320gb.
Later on it will ask for the key, and yes, the key you have is specific to the CD. You can't just download a copy and use it on that... at least I don't think.
The Crapware you have, you can uninstall it. On XP there is the "Change or Remove Programs" and ALSO "Add/Remove Windows Components". Alot of the "Crapware" will be in there perhaps, but I DO NOT see that option on vista. You're going to have to deal with just the plain old uninstall. To disable you can go to start>run (if you have it enabled, if not hold down the windows logo key and press "r") and type in msconfig . You can stop the start up programs from there and disable services. But for the services I recommend going to run and putting in services.msc and going from there. You can disable any of that crapware from starting up.
As for the other 40gb partition you don't know what's up with, with most bought vista laptops they have a recovery part. You can open My Computer and there will probably be three
disks.. the recovery one is probably the 40gb. If not maybe there are two partitions for stuff and the 40gb one is for the OS? No idea about that one