Using excel and google docs

I have several spread sheets in Excel format. I need for different employees to update information daily from different places. Most importantly, due to a government requirement for my business, the information cannot be lost. I was thinking of Google docs... but is it reliable? Does it support complicated formulas? What are the odds while uploading the excel document some of the formulas not properly be copied and I get the wrong results? Any other suggestions? I also thought of using something like drop bucket, but it is not really convenient. All ideas welcome. Thanks!