There are many solutions to pick from, some wont let you play games on both desktops, and some others will.
1. Make new accounts in windows, select switch user instead of logging out, log into the new account. It will be a new desktop.
The desktop that was paused will resume when you switch back to it. This is the slowest way to switch between desktops, but will work on almost any windows pc.
2. If you have a amd card Install amd's hydravision and enable multidesk after installing it. You must assign keyboard shortcuts to switch or shut down various desktops. Once you get used to it, it is easy to use. You can also have the second desktop on a second monitor or use one monitor and it switches desktops on the same monitor. http://support.amd.com/en-us/download/desktop?os=Windows%207%20-%2064
3. Install nvidia's version of this, if you have a geforce card.
4. Windows has "virtualpc" download and install that from microsoft. This option wont let you play games on the os's running in virtual pc, but you can run any operating system that you want including linux without messing up your main os install.
I am trying to get two monitors and two keyboards so two people could surf the net at the same time off of the single pc. Is something like that possible?