If you already got files/documents on your C: drive you can use Partition Magic 8 to create partitions without loosing any data. I've used it myself without any problems.
More info:
http://www.softpedia.com/public/cat/13/8/13-8-2.shtml
Edit: it's always a wise idea to burn your personal files to a CD every now and then. In reply to Ningc_Maniac's post: if you got the OS on CD and your personal stuff, what risk is there? Worst is all files get lost (never happend to me using PM 8) but the only other way is to reformat the HD so it'll be lost then also.
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