AJAX and asyncfileupload on two web-forms

I have two webforms (ascx) where I need some help on AJAX implementation and asyncfileupload. **Asyncfileupload** I need help to some javascript that restrict the upload on filetype and filesize. I should run with the newst version of the ajaxtoolkit. **AJAX** I need the pages to run smoothly on a very slow internet connection (Africa) with AJAX - including errorhandling. I have the whole site on unfuddle and the database on a MS SQL.