For some reason I have lost the ability to have a visual notification of email. I get a sound fine but that is only good if you are at the computer right then.
Owing to the lack of information provided, I'll have to assume you are using Outlook Express in Windows XP. Go to Control Panel (classic view) - Accessibility Options. Click the 'Display' tab. Now tick the box where it says "Use Sound Sentry" and then select what type of visual warning you would like from the drop-down list.