How to assign space from one free partition to other full partition??

You can delete some of your existing patitions and resize D drive using partition magic tool.

For that type of tasks I use Acronis Disc Director Suite. With this program you can resize, move, copy, split, and merge partitions without losing your data. Disk Director is easy in use so you won't have any troubles using it. In addiction it has many useful features like Disk Editor that will allow you to perform advanced operations on your hard disk drive, such as restoration of boot records and hexadecimal editing and Acronis Partition Recovery that will allow you to recover accidentally lost or deleted partitions. Visit Disk Director site for more information: http://www.acronis.com/enterprise/products/diskdir...

I believe that the best *free* way to do this is with a G-Parted live disk, which uses a streamlined version of Linux. This will allow you to resize/delete/create partitions as needed.

I can't but agree with John because Disk Director is really good software. You can merge your partitions just in a few minutes and you can be sure that you won't loose your data.

i'm the third for disk director, but if you are not using server os, there is no need to use server version of disk director(which John S has posted), here it is the right link

http://www.acronis.com/homecomputing/products/disk...