Chinese languages

first of all i apologize for asking a question which is probably way too simple for most people using this forum...
here's the question! five or six years ago i found a very simple freeware which automatically transliterated traditional chinese to pinyin. at the time i wasn't much interested, and i deleted it after a few weeks. six years passed, and now i really want to learn chinese and... i'd love to have an app like that and i've been looking around the web, but couldn't find any. i'm using a macintosh system, so i would be EXTREMELY glad if anybody suggests me a good transliteration app for the mac. thanks a lot!!

i finally found it!
http://www.yale.edu/chinesemac/pages/roman.html
there are many of them, but the most similar app to the one i was using before is "xiaopixie": very good, i would have just preferred to have larger windows to insert more text (the app i was using years ago allowed to insert a whole page...). thanks to all the folks who have read my message!

Is there a similar tool that would work under WIN98 or MSDOS?

You are probably looking for this tool :

http://www.chinese-tools.com/tools/pinyin.html

You paste a chinese text, it adds the pinyin above each characters.