1. you cannot move installed software from one drive to another, all you can do is uninstall it from where it is and reinstall it somewhere else.
2. I'd bet you've got a whole lot of useless stuff in temporary files on your C: drive. Most Windows apps are terrible at cleaning up after themselves. Go to
Piriform - Download CCleaner, Defraggler, Recuva, Speccy - Millions of users worldwide! and download, install (on D:!!
) and run CCleaner, it'll fix up a lot of that.
3. look carefully at what's actually ON your C: drive with Windows Explorer, and in particular look at the size of your user profile directories and the installed program files directories. It seems unlikely to me that just the OS and a couple of AutoDesk and Adobe apps would take up almost 116 Gb. A lot of applications default to storing files under your user profile, which will always be on C:, and that's not where you want them. First rule is, keep the OS, the applications, and the data files, separate from each other. Windows doesn't really allow you to do that, everything you install will insist on putting at least a little something onto the C: drive no matter where you tell it to install itself, but you can minimize it. I never install anything into Windows' program file directories, everything goes into D:\Apps, nor do I store any data files in the default My Documents directory or whatever cutesy thing Win7 has called it, they're all in directories named by subject matter on other drives.
4. don't even think about turning off Windows' update function. It's crucial to keep it up to date to help protect it from security leaks and all the malicious thugs out there.
And just as a point of interest, my C: drive is a 30 Gb partition and it's 35% free space, on an XP system I've been running from that drive for 3 years. You have to be ruthless, and know what you're doing, know where the OS and your applications are putting things, and be sure it's where YOU want them, not where the software designers think is convenient. The do have to pick a default, and they'll always pick C: because every system will have at least that, but you don't have to accept it.