It would be helpful to know just what it is you are intending to install in that VM. For example, 8GB won't be enough if you intend to, say, install Mint 14 KDE and update KDE itself to a later version. But then, maybe you intend to install LMDE, or MATE or Cinnamon edition. Only you know so far.
Mint Testing Team & Mint Donor #3606
KDE 4.12.0, custom preemptive kernel 3.12.5,
Intel i7 4770K @ 4.7GHz, 16GB 2666MHz XMP,
4 Samsung 840 PRO 512GB SSDs in RAID0,
6TB HW RAID10, dual 24" Acer X243H,
Gigabyte nVidia GTX 680 Super Overclock