C# - ASP.Net Ajax Attachment Control

I like to have a ASP.Net Web User Control, which upload attachment like what hotmail dealing its attachment. Done: 1. a ASP.Net Web User Control can upload attachment in asp.net page 2. Demo page is created and proves it is working and working with correct business logic Feature Requirement. 1. User can upload more than one files. 2. once click on attachment link or button, the file dialog pop-up, user can select a file to upload. 3. No html upload file input field appearing 4. Upload the attachment without page postback or refreshing 5. Once file uploaded, you can remove it. by "X" icon 6. If file size larger than 2 mb, show the error message. But don't crash the page. User can continue to upload another file. Environment Requirement: 1. Visual Studio 2010 2. C# 3. ASP.NET 4.0