It all depends on what you want to do. For me, it seems silly to have the ability to run Windows natively in Boot Camp and then have to have another virtual installation of Windows to run in VMWare (or Parallels, which is what I use). Use the Boot Camp utility to partition and install Windows. Then select the BC partition in VMWare as your C drive.
The only disadvantages, as I see them, concern special features that VMWare and Parallels can perform with virtual disk images that they can't perform with BC partitions (such as the ability to take a "snapshot" of the disk or being able to quit the program without having to completely shut down Windows). Other than that BC is the way to go.
As for space, on my MBP, I have a 20 GB partition for BC and use the shared folders features of Parallels to access Mac stuff within Windows. When running in BC, I use MacDrive from Mediafour to access Mac stuff. With a 500 GB drive, you'd have no problems with a 30, 40, or larger partition for BC.
Steve