Is there a good Digital Signage Software available?

There are service networks but all the ones I have looked at require the DS TVs.  They usually have like built in units to play content or have a USB when content can be played.
For providers, RiseVision is one that can intermix your content and from other providers.  Some TVs have built in unit or you could add a small PC to the TV (with right connectors).  Acer makes a small unit we have used.
NEC just opened up their Vukunet software but I have not had a chance to test.  There are also a few limited cost freeware like solutions, but they seemed cumbersome to me to use.
 
Steve
 

Not sure if all this is possible, just throwing it out there. Other experts might add some input.
One homemade option for your in-house marketing is to use Microsoft Powerpoint  to make your marketing material. Then export your Powerpoint to a media that a TV set can handle.  For instance, Powerpoint is capable of exporting a slideshow to a JPEG format; each individual slide becomes a seperate JPEG.
 http://www.graphicregion.com/powerpoint.htm
Plus, some TV sets can display JPEG pictures from Media cards.
Step 1) Make marketing material as Powerpoint Slideshow
Step 2) Export Powerpoint to JPEG, each slide becomes a separate JPG.
Step 3) Put all JPEGS onto the Media Card
Step 4) Plug Media Card into TV set. Each TV can get a different Slide Show via a different media card.
 
 One important item that I don't know the answer: Can the TV set automatically LOOP the JPEG images, or does someone need to advance the images manually? Best Buy can probably answer this question.
 Resolution might also be concern here, need to optimize the marketing material/media for the TV set,
 
 

If you buy a TV-DVD player combo, you might be consider using a product similar to the link below for the in-house advertising. Simply burn PowerPoint to DVD. Of course, the DVD will need to loop continuously. To go to cable television, just switch the TV set from DVD mode to cable TV mode.
 
http://www.ppt-to-dvd.com/samples/index.html#2 

This is a software solution that uses any standard PC to host each client -- so you can use any standard HDTV as your monitor  [but you need a PC connected to it ... the tiny little Acer Revo's wuld be a good choice, or any other small, inexpensive TV].    

http://www.mediasignage.com/

There's a monthly subscription fee unless you build your own server and buy the server license -- but it's free to try with one license.

Seems worth a try -- download the free Signage Studio to create your desired presentation display;   then install the Signage Player to see how it works.     If this will do what you need, it's $41/month for 5 licenses.

Caveat:   I have not used this -- my suggestion is based on reading the details and watching their presentation ... which looks intriguing.      I have no use for a digital signage product -- but may very well give it a try just to see how well it works.

jwooden08,  this is really two entrely separate functions.
But I'd like to add a couple more ideas for you, even though I feel  garycase's suggestion of the Media Cloud is the best really but still very new.
in my humble opinion it comes unstuck here>and also cable television.

Cable TV requires a set top box and a subscription as mentioned,
To see cable tv over 4 different Televisions is possible as this often used in accomodation  in wall cabling is required and a wall switch box.
 also depending on how many channels you want ( one channel per set top box using an rca cable extender. Or go wireless. video audio senders
There are different types of set top boxes here in Australia they are called My Star or the IQ
http://www.austar.com.au/mystar/whatismystar.html
Cable Tv is also available online you can use a little boxee
http://www.dlink.com/boxee/

There is also the option to add a matrox video card to your PC server to send the signal to 4 separate monitors.
http://www.matrox.com/graphics/en/
That would bind all the displays together.

If that doesnt suit
You need some type of media lounge to connect all of it together,
 such as these
Overextended: D-Link MediaLounge media extender review
http://arstechnica.com/hardware/reviews/2008/06/d-link-medialounge-review.ars
http://www.dlink.com.au/products/?pid=547

And to add a completely different route
 CineMassive
http://www.cinemassivedisplays.com/
http://www.cinemassivedisplays.com/dual-monitor.php
CineMastery Software Suite
http://multi-monitor.org/tag/multi-monitor-software/
Lots of choices really a little difficult to bind cable TV to this setup though.
But I hope it has given you some more ideas
Cheers

I have used some of the products Merete suggests and they are good in different ways like the boxee that is cost efficient but not so nice to hide some ware. In your case with a limited budget I think the popcornhour is a good solution.

http://www.popcornhour.com/onlinestore/index.php?pluginoption=catalog&mainItemId=11

It is small and fits on the back of the screen and when it is in place it just runs with minimal maintenance.
/Robb

Hi, since EE is a source for solutions, I feel jwooden08's question is an important one but without a definate solution not recomended to keep.
Delete is ok with me.
It's up to the other experts to concur or disagree
cheers Merete

Even if I do not get the points, I think there is good content in here as I learned about some new solutions in participating.  

Steve

Agree that some good ideas were presented -- it's always a shame when we don't get any feedback on whether or not they were useful ... or even tried.

Agree
lets keep it for our database, the information is good. And I bookmarked it to my knowledgbase.
Personal choice
Accept garycase
you had the most appropiate solution for the question topic
Cheers  :P