Parallels is indeed a great product and addon for Mac. It lets you run Windows along side Mac OS X at the same time. It has let me do basic work that I need to do on Windows like do Java programming.
The basic features it offered were really helpful like sharing dragging files and shared folders. The downside is it sometimes frozed and was unstable, and sometimes doesn't gracefully exit the program. Also windows reactivation was a downside that virtualization gaved me, now I can't use my key and reactivate. Which made me stop using virutualization on my Mac.
Gaming on parallels was also possible with direct X support, it ran the game smoothly, but sometimes the Mac OS X keys interfered. But I don't know about more recent games, it may run more slowly, the game I tried was pretty old.
In Sum, Parallels can get the task done, but if you plan to use boot camp too, I suggest that you don't use virutalization as it will mess your key up.