You ran Linux, OS/2 and DOS and don't understand partitions? Thats amazing. You never ran FDISK? Well that aside, you could always just add an additional partition which will have a different drive letter. Just right click on my computer go to manage and click on disk managment. Select your hdd click on the green area below and right click then select new logical drive.. Now you can specify whatever size "NEW" partition you want. This will not expand your exsisting C:\ partition though. It will however give you more space to save things.. Oh I'm not sure if windows tells you or not, but after partitioning you must format the partition.
Mike