Vista Partition Problem

Hello guys...

I use Dell Notebook with Vista Home Premium. I have 250 GB of HDD and i just recently shrink C: drive from (220 GB) to (180 GB) but i can't carry on after shrink. It said "There is no enough space available on the disk(s) to complete this operation" or something like that.
I can see the newly shrink 40GB partition in Disk Management but i can't do nothing neither delete or format it. It just stay at there useless.
My problem is can i restore my C: drive back to 220 GB or can i format this 40 GB and use it?
Because 220 GB is a little extra big for C: drive(OS). I mainly use other drive for my personal files like D: or E: for music, photos, etc.. but when i bought this laptop, it came with 3 or 4 partitions (i'm not sure) with small size only C: have 220 GB. That's why i shrink the C: drive to get the space i need.

(i'm a beginner in this forum and my english is not good too. So, if found some mistake, pls forgive me.)

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