Clearing Notifications/Downloads Recently bought the Samsung Galaxy Ace and I'm having issues removing the notifications of a download that claims it is still in process, and notifications about messages that are not sent... 

Any idea  how to remove both these things?

Restarting phone hasn't help, nor has "force-Stop"-ing the downloads manager.
If the download is still in process, click the Notification, select the download and Select the 'Cancel' button.

If the download has finished, then reboot your device.

You can clear un-sent message notifications by clicking the notification.