Yeah, I used to do that quite a bit before I gave up on the silly MPG-2 only limitation the Tivo has. Now I just use a HTPC to watch video directly and it pretty much supports any file-format as long as I remember to keep the codec packs up-to-date.
Routers are not part of the equation since your Tivo TOS has you agreeing not to stream outside of your home LAN. You might have a problem with Windows Firewall, but you should be able to easily open up the ports for the Tivo server without problems. I never served media from a PC running a software firewall so I can't tell you what ports the Tivo software uses ... but a google search should turn it up for you.
As I alluded early in this reply, a bigger problem in terms of streaming movies to the Tivo is it's very limited support for formats revolutions. If you go to the appropriate help page on Tivo's web site they lay it out for you. Basically, MPEG-2 format only and a very tight window of resolution, FPS, etc. I found that most things, even if MPG2 already, would not play. And converting to MPEG-2 is slow and wonky. You end up using a half a dozen different methods and programs and no combination of the two seems to work for more than one file ... e.g. you are constantly reconverting because it didn't work.
ElizabethD wrote:Wherever I look, it's all jp1 stuff here, amazing

, even in Hardware
Quick question, NON JP1: does anyone have any experience here with a TiVo network adapter to stream stuff from the computer to TiVo? If so, any issues with firewalls, routers?
PM me or email, please, as I know this doesn't belong here. If Rob permits this to stay here, next one might be about a toaster or something like that.