Missing gigabites

I have a new HP computer with 750 Gb HDD. When I right click C: drive, it says that I am using 90.3 Gb of disk space; however, when I add up all the programs, user accounts, documents, windows, etc... I come up with about 32 Gb in used space. I just upgraded from Vista Home premium 64 bit to Vista Ultimate 64 bit yesterday and saw a 10 Gb increase in disk usage. I removed all the add ons and program stubs from %temp%. I understand bloatware but this is ridiculous. Any solutions to this? Did windows just grab empty disk space and claim it as it's own, showing up as used one way and empty another?

 

Go to Add and Remove Programs and make sure there is nothing there that shouldn't be. I installed vista and all the drivers on a system the other day and when I looked checked there was a 4gig program that I had never even heard of and he definitly did not need.

 

Thanks. It is not this unfortunately. I have about 40 programs on the HDD and all seem to be mine.

 

I just checked my installed programs and they seem to be running fine.

 

A program such as TreeSize will show you what folders are taking up space.
http://www.jam-software.com/freeware/index.shtml

There are system files and system restore files / data that you're probably not adding into the total used. Upgrading the operating system probably did increase the amount of hard drive space in use. Vista is ridiculously space-hungry.

 

Thanks