No need to use complicated or extensive libraries (such as PEAR) to create Excel pages. Just take advantage of the "smart" part of Excel; its ability to parse an HTML table to a nice Excel page.
Just create a regular .PHP file, where you output your data in a nice little html-table. Then place the following snippet in the top of that file (no output can happen before these lines, as they change your headers -- so place these all the way at the top):
header("Content-Disposition: attachment; filename=excel.xls");
And it's just that easy. If you open the page, you'll see a download-window asking you where to place the file. The headers will tell your computer that it's an Excel-file, which will parse your html-table (assuming you've written it without errors) and display it nicely.
If that's not enough, you can look at more extensive libraries such as PHPExcel. As their examples show, it offers more advanced features.