I've got an Apple TV and love it, tho I don't download many movies from iTunes.
I've "hacked" it and run Boxee (
www.boxee.tv) on there, which lets me view lots of other content on there, both from my home network, as well as from the interwebs. You can also run XBMC - another media centre application. It's quite easy to hack although getting your head around the process can be tricky sometimes. For more info, see
http://wiki.awkwardtv.orgAnd as for linking your Sky box to your home router... as far as I know, it doesn't have wifi built in, but I use a Homeplug thingy, which transmits ethernet across the mains cabling. You plug one unit in near your router, and the other in near your Sky box. Each of the units has an ethernet port on it, and they bridge automatically. Works very well!