This is how I would handle it:
Code:
{if $login ne""}
Whatever you want logged in customers to see.
{else}
Whatever you want not logged in visitors to see.
{/if}
so in your case:
Code:
{if $login ne""}
{include file=customer/main/welcome.tpl}
{else}
{include file=customer/main/welcomenl.tpl}
{/if}
I believe it's simply the
"" vs. the
' ' after the
{if $login ne that's messing you up.
HTH