Advantages/Disadvantages of Partitioning a Drive
I strongly recommend you to do the partitioning. It makes sense.
Advantages
- Formatting Convenience - If you ever need to format, you do not have to copy your data out first since it resides on another partition. You can just format the OS partition.
- Increased Security - There is increased data security, since your data is now on another partition. Malware that affects or scan files on only one single drive will not scan your data partition.
- Improved Performance - you can defragment your OS drive for max performance, and not worry about it being fragmented so fast, since data (where it changes the most), resides on another partition.
Disadvantages
- Slower Data Moves - Moving data from one partition to another takes awhile, unlike moves in the same partition.
- Set-up Inconvenience - There are advisable steps to do in order to let your OS use the other partition as data effectively without impacting your workflow. e.g Moving your My Documents folder to the other partition.
- Reduced Space - When you have 2 partitions, some space is lost.
That said, you definitely should partition. In fact, I recommend THREE partitions. OS, DATA, CACHE. Been following this style for years, and never regretted.
I haven't partitioned in many years for now. The only case where I ended up with multiple volumes was when I had multiple hard drives.
When partioning there almost always comes the point where one partition has plenty of space and another one doesn't. And that's when things start getting interesting. Sure, you can solve them by resizing the partitions but I can imagine more fun things to do. Since I have multiple computers retaining data on reinstall is not an issue, it's just a case of temporarily moving the non-replicated stuff over the network. So far worked fine and I haven't had any problems. And I still get a reinstall done in two days (including all software).
In my experience it's just horribly inconvenient to partition which may or may not be a proper reason.
I realize that this is a Windows question and that there are advantages and disadvantages in partitioning but it is worth looking at how Linux distributions evolved.
A few years back almost all of them partitioned heavily between various components (temporary area, a few system ones, user data). I see that this is getting rare now, the main ones just have one large root partition with everything in.