I am running all my test systems off or RPI's. Initially they were very unreliable, which is what got us on the path of customizing MinePeon. Now it's pretty solid. They have their niggles, and of course all things firmware and software are a work in progress, but they should have a 99.9% uptime now.
If you HAVE an extra PC, and can install Ubuntu on it (Windows is not reliable for mining), this is a bit more more stable, but there is a learning curve and you'll have to get cozy with a command line and shell scripts if you want a reliable system.
We hope to release a pre-configured image at some point similar to what we have on the RPI so it's plug-n-play. Until then, unless you are comfortable with Linux, I recommend you stick with the RPI.
-Phil