Not all the advice I've seen about partitioning a hard drive is particularly accurate or beneficial. Of course, we all have different needs and different ideas. The reasoning behind my personal partitioning scheme is primarily to facilitate a backup routine that I can use easily and regularly. The following describes a PC of mine from a few years ago, but the underlying principles are still timely. I had two SATA hard drives on this PC. They were partitioned as follows:
This screenshot was taken when my Primary XP installation was booted. Should these logical drive sizes have proven inadequate at some point, I could have used BootIt NG to resize them.