simple htaccess question for seo friendly urls

I have a static page/script, not controlled by wordpress uploaded in the root level. This page is used to dynamically display the product info for whatever product is chosen on product list pages. In my htaccess file I have the standard WordPress stuff, and I have added the following:

RewriteEngine On
RewriteRule ^product/([0-9]+)/$ /product.php?sku=$1

I’m trying to be able to use product/1234 in the url string but still grab the sku number as a GET variable on my static (not controlled by wordpress) product.php page.

If I delete the wordpress stuff, my rewriterule works perfectly, but of course the rest of the site doesn’t because the wordpress directives are gone. But with the wordpress stuff in place my rewriterule doesn’t work. Any suggestions for me?