You can use the Media Server feature, but I'm actually just building my llibrary like this:
1. Share out your files like so:
\\server\media$
2. Import the files by doing File | Library | Import Media
3. Put the UNC path in the Import box, NOT a drive letter.
\\server\media$
4. Do the import
5. Backup the library by doing File | Library | Back Up Library. Choose your \\server\media$ share to store this backup on.
6. On your Viewing computer in the family room, do a Library restore by doing File | Library | Restore Library. Navigate to your \\server\media$ share.
All your playlists and views will be brought in.
7. Now, rock with the Theater View. Get a StreamZap remote or an ATI Remote Wonder. Either one works well with this program.
All of this works great in version 10. I don't recommend using Theater View in version 11 yet becase there's still some isues that don't make for a smooth experience, but I have total faith in J River... eventually it will be great.
I know that there is a way to actually share the library instead of doing the backup / restore thing I mentioned above, but I also know that I ahve managed to erase my media library several times doing this, and I can't figure out why that happens, nor can I reliably reproduce this enough to inform J River that there is a bug in their software. So I use the method I described and I find that it works very, very well.
By the way, I have a wireless network running (802.11b) and I don't notice much of a problem, but I do recommend a USB wireless adapter so you can get the receiver away from the PC .