You can read more about Googles Advice here, and MSN Advice here.
The following is our advice for you to consider…
People often think that successful SE placement lies in submitting your website to thousands of search engines. Because the major search engines employ fully automated robots known as 'spiders', this is simply not true.
Assuming your page content is optimised, what you need are inbound links.
The backbone of search engines like Google is linking. So the best way to ensure your site is included and ranked highly is for your page to be linked from lots of pages on other websites.
A link from another website in the same field is worth more than a website that is un-related, and the best way of getting quality, relevant links, is to have your website included in related or categorised directories.
Most search engines crawl the web every month and even when you are picked up, your website and any future changes, including additonal links enter what is called a sand box. So it can take time for your website listing to update.