Compiling Data

Hi, I just joined here so this may have been already asked.

I am, unfortunately, running Excel 2003, my organization is really slow in upgrading us!

I am trying to get a worksheet to look at a list of ID numbers that may or may not repeat themselves through out the sheet, but all in the same column for a one week period. What I need is for Excel to return a list of the ID numbers for that week, only giving back each ID number once if it occurs more than once in the sheet.

The ID numbers change from week to week so I cannot give it a specific ID number to search for. I am not sure if that is clear enough or if Excel can even do what I am looking for, any help would be greatly appreciated.

Thanks,
Blair