pretty much anything you want, the is an issue with the images where you sometimes need to add a / but that's about it really. Create some sample products and export them, fill in the template with the data from your suppliers CSV and boom 2k products in around 4 hours work. Oh the default profile is super duper uper slow, if you plan to update a lot do some research and create a faster profile will save you many hours of watching the little green import bar slowly tick up. magentocommerce.com/knowledge-base/entry/tutorial-using-magentos-import-export-profiles