vrijbergen:

Try searching for 'Find Duplicates' in the Excel online help. Here's
what they suggest:

Filter for unique records
Select the column or click a cell in the range or list you want to
filter.
On the Data menu, point to Filter, and then click Advanced Filter.
Do one of the following.
To filter the range or list in place, similar to using AutoFilter,
click Filter the list, in-place.
To copy the results of the filter to another location, click Copy to
another location. Then, in the Copy To box, enter a cell reference.
To select a cell, click Collapse Dialog to temporarily hide the dialog
box. Select the cell on the worksheet, and then press Expand Dialog .

Select the Unique records only check box.
Note Once you filter for unique values, you can copy them to another
worksheet and then archive or delete the original worksheet.