Partition magic can be downloaded free, which shows you what you can do with it. However I don't think it does anything unless you buy it. If your not confident go the easy way.

My solution would be to disk anything you want to keep and do a clean install of windows. Delete all partitions and create a new C and D. I only use an 80g hard drive and I have 30g for the OS [C] and 50g[D] for data storage ect.
It's easy to do and if you don't know how then google it.

Unless your into downloading movies or heaps of music, anything more than a 100g HD is a waste of time as nobody has data enough for anything bigger and defraging these new giant HD's is a pain [unless you have 'Executive software Diskeeper', a separate defrag. [not free] that does the job quick smart and even defrags. the paging file. I use it even for my small HD. It takes seconds.