I need help partitioning my C&D drive for Sony Vaoi tower

I need help with my Sony Vaio XP dual drive 16 gigabytes C drive & 60 gigabytes D. I'm out of memory on the C drive...well almost. I uninstalled most of my software. And something is still eating up the hard disk space. I put all of my photos and music on a 1 T external drive. I still can't figure out why i have so little disk space on C. I bought my Sony in 2002. It's very slow, I can't update DAT files or updates. If I could make the partition bigger than I'll have more room but I don't know how to do that. Also I would like to restore some old files that I compressed two years ago. Is there hope for my pc?