TeamViewer is a very easy to use remote desktop software that offers file transfer is very secure and has many interesting features.
I like it really because of simplicity, security and ease of use. Sessions are password protected in order to connect to another pc, which makes it nice, because you can have it running on a computer and anyone can connect to it if they know the password. This is extremely convenient if you have a client, who constantly needs remote pc repair and is not available at his computer to initiate the session.
or if you work from home and would like to access your computer at work, this program is also a must have.
it has many different features like VPN, file transfer, presentation, etc.
best thing about it. it is free to use if you are not using it commercially. so check it out at www.teamviewer.com