The client installation is a bit confusing in the beginning and you'll have to look in forums for different explanations regarding the Client Ninjam configuration.
Tip: don't use the basic Client Ninjam and download Reaper for Ninjamer.
The Client Ninjam doesn't require a powerful system but you'll need to have a fast internet connection, ASIO drivers for Windows, and line and instrument inputs.
Take your time with the ASIO settings under Windows to minimize latency!!
I've been using Ninjam for over two and a half years.
It's very useful if you want to practice, develop your style and test new music styles.
The only disadvantage the learning curve because of Ninjam's conception.
But it allows you to play live any time and that's priceless ))