Transparency In The Gimp And Gif Formats how do I save a GIF with a transparent background?

[shadowx 0]

Howdy everyoneI just spent a while making what i think is an alright first sig but i need the background to be transparent and when i save it as a GIF it isnt. Im using the GIMP to do it in and in there its transparent, i saved a copy (so not to ruin it when i flattened the layers) selected to flatten the layers rather then save as an animation (although i have tried that too and got the same result) didnt covner it to greyscale as its in colour and saved it. when i view it it has a white background instead of transparent and i used a little html test page to see if it was really transparent and if it was jsut the image veiwer not handling it well but its not transparent its still white so how do i save it in a form that i can use on the web and also that has a transparent background?Thanks hope someone can help.