Everybody knows that the majority computers have the OS on the C: drive and most people are used to this configuration. Although, in most situations, it really shouldn't matter on what logical drive your OS resides, it might be annoying or confusing to some users to not find Windows in the "usual" place. Most of the time when you install windows, it will correctly resolve to the C: drive. However, if the computer comes with removable media drives for memory cards, depending on many factors, Windows might install to a logical drive letter that comes after the removable media drives. If this configuration is undesired, then simply disconnect the removable media drives from the motherboard and redo the Windows installation.
If you decide to stay with your OS on a logical drive other than C:, then you shouldn't experience problems as most programs use environment variables to install. An environment variable is a special DOS level variable used to store useful system information. You can see your systems environment variables by getting to a Command / DOS prompt (start/run/cmd) and typing "Set". As you can see there are variables like "System Drive" that point new programs to the correct logical drive for default installation.
Should you ever run into any suspicious problem during install as I did recently while installing the Flash Player for internet browsing, there is a simple workaround.