Download Repository Not writable ERROR message. Please help

[starxox]

Hi there

I'm trying to add some downloadable products to my site but when I check the box it says

"Your download repository is not writable"

where is the download repository - is it the upload folder? If so my folder is at CHMOD 755 (because my permissions are set up in such a way that I never need to use 777)

Can any one help

Many many thanks

StormJewel

ps already added a similar post to another thread but realised it was over a year old so thought I'd start a new one