ProgressBar for xmlHttpRequest

hello,

I have an activeX app which is used to upload and download files, the way is does this is by encoding and decoding the files into xml then using the xmlHttpRequest method in VB to and from asp pages on the server which encode/decode (depending on up or download) and save the faile back in its original state.

To get round the progressbar issue over http what I have done is calculate the file size , estimate the network speed then divide the file size by network speed, set a progressbar max value to the result and fire off a timer which runs until the progressbar reaches its max value.

This isnt too inaccurate but I can forsee future inaccuracies with larger / smaller files and varying internet speeds.

SO can anyone suggest a way or gettting the progress of a file transfer using the xmlHttpRequest object

e.g getBytesLoaded in action script?

many thanks.