Hard Disk Size for OS

go to your user documents and transfer them to other drives,also downloads can be transfered to other drives.

Of course you can do without reformatting.. Could you pls confirm me the current OS installed.. So that i can easily guide you accordingly. If you are using windows 7 or vista means there is a option to partition shrink.. If not we need to use some third party tool like partion magic.It will helpful..

The best way for you to do here is merge the 10 gig of hardisk space with one of the 40 gig partition. You can do this by using a software call partion magic. But be careful not to erase the contents of the drive. For precaution make sure that the 40 gig has no files in it. It is okay with the 10 gig since the OS is installed in this drive so windows won't allow any deletion of the OS. Take note that an operating system requires a large disk space in order to run smoothly. Space affects speed and performace. Hope this helps!!!

i didn't get you, according to your discussion you have a total of 170 gb. but whatever the case be you will have to use the windows administrative tools to delete a drive (make backup of that first) and then add it to the current window drive.