I want to increase the size of one of my Hard Disk partitions (want to move space from the OS-drive to a non-OS drive). I can't seem to do this using the Disk Partition tool that comes with Windows 7 (I can create new partitions but can't shrink and add to the non-OS drive). What would be the simplest way to go about this without partitioning any of my drives?
You're confusing me a bit with your terminology. When you say "non-OS drive", are you referring to the partition which does not host your operating system? For the rest of my post, I will assume that's what you mean. If it's not, ignore the rest of this post and explain what you mean.
First of all, it's never a good idea to shrink an existing partition which hosts your operating system. For the ease of explanation, files on your computer do not line up neatly in a row on your hard drive, they basically land the first place they can find. While it won't necessarily corrupt your operating system, shrinking your operating system COULD lead to inability to boot into Windows 7.
However, if you are sure this is what you want to do, I recommend downloading
GParted and burning it to a disc (use
ImgBurn, since you want to make the disc bootable). Once you have GParted on a disc, place it in your DVD-Rom drive and reboot your computer. You might have to go into your BIOS and change your boot order to have your DVD-Rom drive boot before your hard drive. Once you boot with GParted, it's fairly obvious how to adjust your existing partitions, allocating how much space on the disk you want to each partition.
Again, remember it's generally advised not to shrink existing partitions which host your operating system (unless you simply don't care to reinstall Windows in a worst case scenario).