Yes, your answers help in narrowing down the range of options.
As for wireless solutions, there are several to choose from.
Hardware:
I'm not familiar with the PS3, but if it has a wireless card in it that allows wireless access to the machine, that would indeed be a way to go. Check the software that comes w/the PS3 to see if it's compatible w/Lepoard or Tiger (check your OSX version -if it's 10.5.x it's Lepoard, if 10.4.x it's Tiger)
Other options include the AppleTV and other devices. Check
this link for a list of other devices (under the forum heading "General Discussion about UPNP/DNLA and other TV connected devices".
Software:
To manage the files you'll need a media manager. Each device above will have their own in-house software which may or may not suit your setup. I have a Phillips Media Manager SL300i and instead of using the Phillips software, I use TwonkyVision. TwonkyVision is one of a number of third-party media manager programs that will work with a variety of devices. Once installed on your computer, you can sit in front of the TV and play the file you want from the GUI displayed on the TV from the attached device that connects to your computer wirelessly and away you go!
Here are a few links to get you started:
TwonkyVision
MediaTomb
Here is a general article on setting up a Home Media Center on the Mac you may find interesting.
Ed