Optimizing Parallels 8 on a MacBook Pro 13" mid 2010

Hello!

Recently I bought Parallels Desktop 8 and I'm fascinated! I'm using it with Windows 8.
I need some advice on how to configure the Virtual Machine, so I can use more graphically intense programs as games.

The laptop has:
Intel Core 2 Duo 2.66 Ghz (2 cores) - I allocated 2 out of 2 cores for the VM
8GB of DDR3 RAM - I allocate 3 or 4 GB
nVidia GeForce 320m (256Mb shared graphics card) - My problem is here! I don't know how much VRAM I can allocate.

Please give me some ideas on how to best configure the VM.

P.S. Currently the game I want to play is Heroes VI.

Thanks in advance!

 

No one can help?
Please, guys! I need to know how much VRAM should/can I allocate having in mind that GeForce 320M has only 256MB shared memory.
What happens if I allocate up to 1GB of VRAM as the VM let's me do?

 

Try it yourself, it doesn't cause any harm.