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#11
One thing that I haven't seem mentioned: are you using hibernation? Windows creates hiberfil.sys, which is the same size as your physical RAM (4GB). If you don't want to use hibernation (which is quite different from S3 sleep), get rid of it.
What is hiberfil.sys and How Do I Delete It? - How-To Geek
My Windows folder (7 Pro X64) comes in at under 20GB, by the way. I don't regret buying a 120GB SSD for my boot drive, though. Allows me to be a bit more careless.