I dont browse the net on my arcade machine. Windows updates come from the local wsus server, it has no default gateway so it cant get on the net if it wanted to. Install files I download to my raid and keep, so anything dodgey will come up when I am downloading on the desktop. roms are torrented on a desktop computer to a network share on the arcade machine so once again, no need for direct internet access. I am planning on streamlining things for when I build another machine but till then the manual way is fine. I would like to build a single image that I use on all machines but thats effort I cant be bothered with at the moment.
I did let it on the net for a while so minilyrics could get things, but now I just search albums as I add them to my raid on my desktop computer so they get downloaded at that time, then they are there for the other computers.