looking at that diagram, I think that what you want is this:

1) a dedicated router, R1 which is your access point for your internet. You want this to be wirelessly connected to the laptop and connect via LAN to the desktop. This is done by any new router-modem.
2) You want to set up a dedicated home network (HN) (to share a media center?) which is not connected to the directly to R1, using a secondary router R2. This HN is based as such that now, the PC is connected to the R2 wirelessly, while you laptop is connected to via LAN.

I have a question. why do you need R2 in the event that you are connecting PC to Laptop? Why not connect it directly? Adding a PCI Lan card, you will get an additional LAN port that can be connected to the laptop's LAN port.

for what purpose do you need two routers for?