Gateway has a progressive-scan DVD player that streams content from a PC. It streams music, photos and video from a PC with built-in 802.11g. It looks like it supports MPEG and DivX video files.
PVRblog has a review of this player. The DVD player has a price of $119 on gateway.com.
One downside of this DVD player for me is that there isn't Mac OS X or Linux server software for it.