Here is an excellent video on various changes you can do with folders in Windows 7:
But I do not believe that I have ever seen anybody post information about an ability to change a folder name to a bold font. I believe I have seen something about third-party software, but that was a bit back and I may not have even saved that information on another unit here at this work station because I would not recommend any third-party software be used for this purpose, if it is even available.
I recall some sort of manipulation being possible with icons, but I must apologize for not being able to remember if that is shown in that video I gave you the link for.