With the old uploader there was a list of file size limits and I remember them to be fairly large, especially when it came to zip files. A single Excel file that was zipped might still be small enough to upload directly to the forums.
The mods should be able to find out the file size limits and let you know if the zipped Excel file falls under that limit. 8)
Wheels
Edit:
I found an old picture I used for another post regarding the uploader and certain files allow a 150MB upload while the pictures are limited to 5mb. I seem to remember that .zip files and .rar files also allowed a 150mb upload. I would think just about any zipped Excel file should fall below 150MB in size.