Microsoft Remote Assistance
Microsoft Remote Assistance (see Figure 2) is included free by default in Windows XP and later, so no downloading is needed. It essentially provides a basic version of Microsoft Remote Desktop, but is targeted to providing assistance.
Troubled users can invite you to help via a Windows Live and Windows Messenger account, email (if using Outlook), or manually send/share an invitation file. If both computers are running Windows 7, you may be able to use Easy Connect instead. Or if Group Policy has been configured with the appropriate settings, you can directly connect by entering the remote computer’s IP address.
It offers basic functionality: You can see and control their desktop, send files, and chat. Nevertheless, it is a completely free solution for personal and commercial purposes.
The problem with Windows Remote Assistance is that you can experience connection and firewall issues because it uses port 3389. Though port forwarding isn’t needed, like when using Microsoft Remote Desktop, there can still be firewall issues. There are less issues if working on computers that are connected to the same network and are all managed by you.