Originally posted by xotix
if your computer isn't top of the line, its better to make one big partition than two smaller partitions, reason being virtual memory is going to need that hard drive space.
It's not about what kind of computer you have. It depends on the file system you're using, the purposes of the PC, and how large of a HDD you've got.
There are several reason why partitioning maybe useful. As mentioned previously, it's almost essential to have when you're dual- or multi-booting with different OSes.
2nd: On a large HDD, in order to minimize the slack space and keep your cluster size down, you should partition it accordingly whenever you're using a FAT/FAT32 file system. When using NTFS, the cluster size is always at 4 kb so partitioning becomes less of an issue.
3rd: Backup. When you keep all your personal data files on a separate partition (apart from your OS files) it becomes very easy and convenient to use a ghosting program to target a specific partition to backup onto another drive or partition.
Now does this mean that if i dont' partition my HDD i can't make a backup? Of course not. The point is that it makes life easy on you by eliminating errors and improving efficiency by doing so. For people like myself who have a lot of personal data to store and backup, it's extremely useful as I don't have the time nor inclination to pick and choose the dozens of folders I have.
My personal advice is that you're never done learning about computers/internet/technology. Once you think "I know it all"... there's always someone more experienced and more knowledgeable than you to put you in your place. Being humble and keeping an open-mind never hurts.