Does it make a sense to use Parallels?

There is Intel Core 2 Extreme Q9300 Quad CPU on my notebook (M6400) + 4Gb DDR3 RAM + NVidia CUDA (48 GPUs)
The host OS is Windows Server 2003. Now I am choosing between the virtual machines - VirtualBox, VmWare and Parallels. I 've been working with VmWare previously and not familiar with VirtualBox and Parallels.

The question is - which VM will utilize hardware resources of my system in the best way? I need to virtualize UNIX and Windows systems on my host.

Thanks!