N.B. These instructions were written for Windows 7, but should apply to other versions of Windows with minimal modification.
You can check whether or not you have a Windows roaming profile by firstly clicking the Start button, right-clicking on "Computer", and selecting the "Properties" menu item:
Then, in the left sidebar of the window that appears, choose "Advanced system settings":
A dialog box entitled "System Properties" will open. In the "Advanced" tab, click the "Settings..." button in the "User Profiles" section:
A dialog box will open which shows you a list of the profiles currently stored on your computer. This dialog box shows you both the "Type" of your profile (which will be either Roaming or Local), as well as its size.