Summarizing with information from multiple columns

Hi all-
I have a spreadsheet which I generated from my point-of-sale system which lists information such as:

LastName, FirstName, Category, Price

Each purchase by each customer has a separate line item, and I'm trying to find a way to determine which category each customer purchased the most number of items from so that we can execute a direct mail campaign.

For example, the spreadsheet could have data such as:

SMITH, JOHN, CATEGORY-A, 10.99
SMITH, JOHN, CATEGORY-A, 29.99
SMITH, JOHN, CATEGORY-B, 16.99
DOE, JOHN, CATEGORY-C, 19.99
DOE, JOHN, CATEGORY C, 10.99
DOE, JOHN, CATEGORY A, 11.99

John Smith purchased more items from Category A this month, so I want to put him into a separate list from John Doe, who purchased more items from Category C this month.

Any idea how I can accomplish this with Excel? Or maybe this is more an issue with how I'm exporting the data from my SQL server?

Thanks much.

You might be as well doing a pivot table, with the name (assuming they're unique, you'd also be better concatenating the first name and surname) as row and the category as data and column (or vice versa)