Ok so the router is out of the question

I was thinking that if the router can handle seeding +20 torrents in the size of a few GB with a connection limit set to 500 and it does not slow it down that it could power a node.
What about an old laptop, 2GB RAM, 1.6 Ghz Atom processor? Is that over the top or would it barely handle it? I don't want to run a node that would just slow the network down and do more harm then good...
We are talking about a Raspberry Pi and the ODROID-U3 now, the second one has a quad core. So what is the reasonable CPU to handle the node, is the Atom good enough?