I am digging and digging and not coming up with a clear answer of how to restrict the upload of files and images to the media section in the backend.  We need to do a few primary things such as:

• Prevent a user from uploading a huge file
• Block a user from uploading a restricted file such as an ASP or HTML or Zip file
• Allow PDFs up to 5MB but images no larger than 300k
• Block images larger than so many pixels

I've tried a few of the add on uploaders but each leaves something out or does not allow restricting the uploads. What are you using?  What do you recommend?