There are hordes of combinations that could suffice for this purpose.
My most recent setup is an older Airport Express Base Station connected to my older Onkyo AV receiver via digital optical in. I stream from various devices over the network using a combination of Airfoil (software) & VLC (media player). Most of the computers involved are running either Vista or W7, and there are a couple of iPod Touches in the mix too.
I also use a WDTV live which connects to another AV receiver via HDMI. An external HDD & various large USB flash drives are connected to the WDTV and contain the media.
I have a large collection of music on a network connected HDD and at the moment select and play tracks using MediaMonkey on my WiFi networked laptop, which in turn is hardwired to my HiFi amplifier. This is very awkward if I want to use the laptop for work.
Can I connect a Tablet or netbook that will perform the same task, running an app that acts like MediaMonkey?