There are a couple of ways of doing this. Assuming that you have a wireless router than a wireless bridge like agarwalro suggested will take the place of running cables from the router to your PC. I own the model that he suggested and it's a good unit once you get it setup (plan to set it up manually because auto setup didn't work). But it simply takes the place of running a cable and isn't a media player. It's a good choice if you want to connect up to 4 devices in your entertainment center to the network and the bandwidth requirements aren't huge.
Another option is a wireless network media player like the
newest version of the
Western Digital TV Live (~$90). The WDTV Live connects to your system via HDMI and uses your TV as the display. I had the older non-wireless version and it does a pretty good job. As long as you have a TV at that location to act as the display it's a good solution and supports most audio formats although FLAC files are limited to 16bits/44.1khz (CD quality) and supports most video and photo formats. It does not require setting up anything on your computer other than a network share.
There is at lease one media player on the market that has it's own display but I have no experience with it.
The other and I think better option is to run cabling from the router to your entertainment center. It's a pain in the butt but you only have to do it once. The reason that it's better is that it provides more bandwidth should you decide to play Blu-Ray quality video across the network. Wireless just doesn't have the ability to handle the 10-12GB/hour needed for Blu-Ray. What I've done is run a cable to a switch in my family room and connected a Netgear
NeoTV550. I chose that model because it supports 24bit and multichannel FLACs - but it does not have built-in wireless.
