Creating new partitions in windows 7 installation

Well I just reinstalled Windows 7 and although all went fairly well I was unable to create the partitions I wanted . When it came to the options on partitions I was presented with 2 partitions, one which I could not increase in size over 101mb and another 931gb partition. I could format the drives, and I tried resising the 101mb one, but there was no option to create new partitions. Maybe Im being really silly and missing something here, but could I get some help?

What I want:
1x 50gb partition for OS (C:\)
1x 930gb (or what ever is left) partition for files (D:\)

So...how could I accomplish this?

Thanks :P

Please upload a screenshot of your expanded disk management layout so that we can help you further.

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I would add that the 100MB partition shouldn't be touched as that will be the one holding your boot record.

Oh...One thought...:P Could it be that all available space was in use? Like If I changed that 931gb partition into a 50gb partition perhaps then it would allow room for another partition...but how do I select which drive windows installs on?

Please post a screenshot of your hard disk layout as it will help us to help you.

Yeah, Sorry, Just had to make room for more partitions by decreasing the size of others (derp). Thanks anyway :)