it's probably the updates then. mine is a clean, fresh install. and yes, 64bit has a bigger footprint.
don't see how the point stands when i've just proved otherwise. and this is a dual boot. for a single OS, 40gb itself would be overkill. of course i'm not talking about installing games, which would involve several gigabytes each. i have all my games installed on my storage hdds.
remember, the op is probably on a budget, and for those kinds of people, myself included when i got my ssd, 30/40gb is enough to run an os and most common apps. my acrobat and photohop cs folders in program files total about 600mb, office2003 lite is 65mb and Office 2007 is 335mb. how much more space could you possibly need. of course 256gb is awesome but not everyone can get one.