Maintaining A Sorted List In 2003

I have an Excel sheet with a list of data, which is likely to change frequently and has to remain in sorted order.

Requiring that users of the spreadsheet maintain the data in this way (i.e. sort it every time it changes) is a really bad solution and I'd rather not use a macro if I can avoid it (too much stuff can go wrong).

Is there a good way of doing this? At the moment, I've implemented merge-sort within a sheet, which works, but is a heavyweight solution, taking 6 columns per merge-sort iteration (so 60 columns to sort 1024 rows, 96 columns to sort 65536 rows). I could try to compact it, but my head was starting to implode programming it even with as few as 6 columns.

There must be a better way of getting Excel to maintain an automatically sorted list.