How to customise post listings template for a particular category?

Hello,

I have a twentyten child theme and a category called “all-projects”.

I would like to create a customised layout for how all posts under this category are listed/looped.

I’ve seen the category.php and loop.php files but I don’t think I’m supposed to mess with this as it will affect all other categories as well.

Anyone have any ideas?

Thanks,
Kristy