.NET Repeater Conditional Template?

I've got a repeater which is pulling items from a database. Some items have a link and some have null filled in for the link column. I was wondering if there is an easy way to format those with links to have an <a href> tag around them and those that have a null link not to be formatted with the surrounding <a> tags. Is there a better way than to just do an if...else clause?

Thanks.

edit: also is there someway I can tell the repeater how often to render the seperatortemplate (i.e., print a horizonal rule every three repeats)?