Desktop application development

Hi We are planning to develop a desktop application to distribute education content to school and college students. The wishlist for the application is like this.. 1. It should be compatible to multiple platforms....atleast windows, mac and linux. 2. It should be graphically rich and the user experience and interaction should be engaging. 3. It should support content in various formats like....Videos ( flv/wmv..?), audio, images, interactive animations, pdf documents, java applets/simulations, html text, flash games etc. 4. The content should be protected and be limited to licensed users only. 5. The content can be streamed online and downloaded to local computers as well for offline viewing, but users should not have the access to the downloaded content outside the application. 6. The application should be able to communicate with hardware like CD ROM, USB ports, webcam and microphone etc.? It can be used to download the content in portable media devices or the content can be updated from CD ROMs as well, instead of downloading from internet. 7. The file size of runtime/installer should? be of minimum size so that it can be downloaded easily from internet with normal broadband connection. 8. The application performance should be good on low end processors like Intel ATOM with 1 GB RAM. ( Most of the kids would have low end computers.) 9.? It should have an integrated browser with parental control to view suggested webapges. 10. It should be able to communicate to the OS libraries and files to start external programs. Like if it is being used on windows, we should be able to call external exe's or Dll files from this application. 11. We would like to integrate lots of readymade widgets ( open source tools for education) and content with ths. So the platform should be open and scalable enough to incorporate the same without much restrictions to supported formats. and lastly the development time should be minimum as the application is to be distributed for free. We are looking for a suitable technology platform as well as developers to develop this application. Some of the options that we have explored are....Adobe AIR/WPF/python/QT/silverlight/<wbr />titanium.....? Please let us know if you have a solution for this and would be interested in doing it.? Regards Rohit