Windows remote assistance should work for you as it is included with Win 7. As long as you're on the same network that should be fine as long as the administrator hasn't blocked the ports. Otherwise if this is over the internet there's plenty of free services like teamviewer that would allow for desktop sharing.
Netmeeting has been decommissioned since Windows Vista and hence it cannot be used in Windows 7. There are alternatives to net meeting such as WebEx, gomeetnow, gotomeeting etc. Alternatively, you can even consider deployment of on premise desktop sharing appliance such as RHUB appliances.