Exclude posts with ‘tag’ from index page

I am aware you can exclude categories from the main page through various methods including the ‘front page excluded” plugin. I am in need of excluding posts with a particular tag from the main page of my site. I’ve read several posts of using queries within the loop, but they seem to be for previous versions of WP. I am using WP 2.5.1 with the Prologue theme.

Cheers