Another virtualization software is called VirtualBox. There are PC software that work with CrossOver which doesn't need windows, but isn't compatible with all softwares.
Native speed
- Bootcamp
Needs a copy of windows, XP SP2 or later
Virtual Machine (runs besides OSX)
- VMWare
- Parallels
- VirtualBox (free)
Some can use partition made with bootcamp, then you have the best of both.
Needs a copy of windows, XP SP2 or later
Doesn't need windows
- CrossOver
- Wine (if you are the tinkering type)
Compatibility is limited, but less resource intensive than Virtual Machine because it doesn't run full windows os.