Hello!
This may not be as simple as it may sound, so I am putting some safety margin time-wize.
Now, what do you know about this file`s contents/organization? What size the file actually is (transferring over Internet would have to occur in any case, so this is important)? What is the message Excel is giving you when trying to open and render the file? Do you know anything about how the data is organized in the file - is it one or multiple sheets for example, how the data is laid out in any particular sheet, what are the embedded images (I am assuming they are embedded because of the size) - proper image files or excel/office objects (like graphs etc.) etc.?
What is the originating version of Excel, of the file, and office for what OS (Mac or Windows) was used to create it?
And last, though not by importance, how do you want the data split - to any particular file size, each sheet (if multiple) on its own, but not chunked itself, the images taken out and the rest of the content left as is?