Creating multi-user Excel form for online
 

I have created a spreadsheet listing auction items. The columns show the
retail value, current bid, minimum bid, etc. These fields have associated
formulas. There are three columns that are not locked and can receive
entries. I want to be able to somehow use this spreadsheet on a private
website for members to bid on the auction items. My problem is that as a
spreadsheet, the user must first have Excel and then must save the
spreadsheet to record their bids.

How do I get around the need for the user to have Excel?
When saving it, is it saving to the website file or to that person's hard
disk?

I like the Excel form, but can't find out how to just show users the form
instead of Excel... HELP! I also tried converting to PDF, but then you lose
your formulas.