i wouldn't recommend running more than 1 virtual machine. There isn't a problem wit hard drive space but everything else becomes a problem. From what i understand abt virtual machines is if ur cpu is multicore. each VM will take up one core. If single core ur basically making the cpu switching between processing stuff on ur native and than the VM. Ram is also split is the same concept if u run 1 VM half is native and other half in VM. and if u think more deeply the chipset usually can only process a certain amt of threads from the CPU to other hard ware components. The split works in the same way. Unless you somehow set the priority for the native to run higher than the VM. But than the performance in VM will drop like a brick. So ya my advice is to just run one VM anymore than 1, the system is gonna get really taxed.