getting data from columns to rows without using transpose

Hi, I have an excel spreadsheet which contains data for customers and the last date they were seen at an appointment (along with various other bits of info). The way the data is exported from my database package means that each customer has one row per appointment, i.e. row 1 contains john smith, 01/01/2009, row 2 contains john smith, 03/03/2009, row 3 contains john smith 01/04/2009, row 4 contains joe bloggs 12/02/2009, row 5 contains joe bloggs 27/03/2009. Some customers may have 4 or 5 appointments listed whereas another customer may only have one. I need to get the appointments all onto one row per customer so that I can calculate the number of days between appointments. I have tried to use transpose, but with 8000 rows it takes forever! Any help would be much appreciated. Thanks Rachael