If you want 2 boxes then you'll need a router - each box will want it's own stream. Even if you want just 1 STB and to be able to use your PC at the same time you'll need a router.
On the laptop side of things, you can connect it directly to the modem but again it depends on whether you want the laptop on at the same time as the desktop - or if you want the laptop wireless.
If Sky Sports and Sky Movies are must haves, then you've ruled PlayTV out completely - they don't offer either of them.
I'll be interested to hear of their responses to the other questions though
