How to give an access to single person in excel 2007

Hi Guys,

Im the authorised person to edit or do any modifications on the excel file. I need to protect it as it should not be modify by others. The purpose of the excel is im assigning works to others where they could find the request assigned to them. At the end of the day i will put the status in the excel by checking their work. Others will be opening the file in read only, but if i assign the work in between and ask them to check, they are closing and re opening the sheet.

Is there any way, if i make changes and save the file. Others can view it without closing and re opening it.??

Thanks,
Shiny