http://www.sitemaps.org sitemaps are really just Google XML sitemaps with another version number. You just need to use one of the sitemap kinds. Decide if you want to use XML Google (http://www.sitemaps.org), RSS or text. Google and Yahoo support all formats now. In addition to one of above, you may consider creating a HTML sitemap for your human visitors.
My suggestion is that just keep working on your web pages, forget sitemap and just keep getting backlinks by submitting to directories, post in forums, and wait google to crawl and index your pages itself. If you really need a standard sitemap generator, please try this one: www.hkhangfong.com/service.htm . Since you have 1500 pages, you shall download a desktop version of sitemap generator here: www.hkhangfong.com/service/freesoftwares.htm