[justbondage]

There is no issue with having multiple sitemaps.

Basically it makes indexing your site faster because google can zoom through all the pages listed on the sitemap with ease, as opposed to following links on your pages.

It is especially useful if you have dynamic content like index.php?page=wibble (assuming the value of page changes each time) without a sitemap, there is a chance not each page will get indexed, which is obviously a bad thing!

The reason you have such a range is some programs are very simplistic, and list the files in directories, which is great if all your content is .html and .jpg etc etc - others will go into more detail and list dynamic stuffs - you want these listed (for that reason above).

Google Webmaster Tools is an excellent resource. Really top notch.