Do virtual machines run even when you don't have them open?
You can run them in the background.
If so, how many virtual os's can run simaltaeously?
It depends on how much RAM and CPU power you have.
Another question, is there a way for having multiple win 7 user accounts to run their own programs simultaneously?
Yes.
If I acquire a license for VMware workstation, can I use it on both my laptop and desktop?