Whole House Media setup???

Hello there. I am new to this forum and new to Media Centers. I have been building computers for a long time now just never got into the Media center side of things. I have a few questions about it. I have recently canceled my cable in hopes of saving some money in the long run. This is what I would like to do please let me know if it is possible, I might be asking to much...but here goes...
I have 3 plasma hd tvs along with 2 old tube tvs. I also have an antenna mounted on the roof for OTA HD and I am thinking about getting basic cable. Now with that said I would like to setup a whole house media server/media center. I would like to wirelessly stream live tv to all the tvs, with the option to record one show per tv at the same time. I have been looking at the DSM-750 for the streaming live tv and pulling recorded tv off of the media center, I am just lost when it comes to Media center and the requirements needed to accomplish what I want to do. I will be building this computer (Media Center) but not sure of the power it would need to have, also I am not sure this extender is the most effective device out for the job. If there is anyone out there that can help me in this endeavor your input would be greatly appreciated. I know this may have been talked about in other threads, if it has please piont me in the correct direction. Thanks

Hey thanks for the fast reply,

As far as the Plasma's I know that they do not have any sharing capability build in.

As far as watching tv on the computer itself, we will not be doing that it will be solely used as a media server. I am more or less trying to replace the Comcast HD DVR due to the $16 a month per unit charged for them. I will defiantly look into the WD products.

I think I have the build down so far. AMD X4 955, Gigabyte MD, 8Gb ram (because its cheap) and about 4Tb of space for now, and a 9800GTX vid card.

I was under the notion that I would need a separate TV tuner for each tv, is this correct? If so I am going to go with this one
Hauppauge WinTV-HVR-2250 Dual TV Tuner / Encoder 1229 PCI-Express x1 Interface - OEM http://www.newegg.com/Product/Product.aspx?Item=N82E16815116037
Is this a card that will provide a good HD quality?

Can I stream the Homerun product through WMC? Or would that just be for watching tv on the computer?

Okay so I have reconsidered the whole setup thanks to the home run and the cost of the dsm-750. I am thinking I will get 3 media center computers. EL1358-UR20P Desktop Computer I will put a wireless N pci card in each and have a N router that they all connect to. The HDHomerun will be attached to the router. Now I have a question about the Homerun...Will I need 3 to stream live tv and record for each tv if I want to watch them all at the same time?

*UPDATE* Just wanted to update this thread because I can remember searching this topic and seeing no end result. So what I ended up doing was getting 3 new computers for the 3 Plasma's each with windows 7 media center(the 2 analog tvs are just hooked into the wall), an HDHomerun Prime, Gigabit wireless N router and 2 wireless N PCI cards. With this hardware I stream hd video to 2 of the computers and the other is hardwired.
As far as the OTA tv I ditched that idea and went with basic digital cable and internet. I now pay about $73 a month and have 3 hd DVR's (WMC). This was a great money saving venture and has worked out very well.The entire system should will pay for itself in 9 months. The TV's have an awesome picture! and recording is as easy as the comcast dvr's ever were.HDhomerun is a must have! I think I may pick up another one so I can record more....Well thanks again to all that helped!