Hi, I know Mediaportal is designed by .net, and now it's only windows version, is there any way to port this exellent S/W to cheaper box? maybe the cpu A8, 1G, 4GB flash and 512m DDR.
It would require a complete re-design and re-write from the ground up, written for linux. In addition to .NET, MediaPortal takes advantage of microsoft's BDA, and DirectShow filter frameworks, among other things. Your best option is to set up aMPdroid, but even that isn't a perfect solution if you are trying to run it as a HTPC.
Technically, there's nothing stopping a client being built for Android that could use a native stream. So, for example, you could run an MP server on one machine, and have a phone / tablet / GoogleTV as a client. I already do this on my phone and tablet using aMPDroid, but I use an encoded stream. This works really well.