To open in a new window, hold shift when you click the link. To open in a new tab, hold control when you click the link. You're in control of where links open and websites don't need to do anything to give you that control.
Can you add an option to add Hacker News to my Internet Explorer favorites? Also, can you add an option to make Hacker News my Internet Explorer home page?
IE 8 opens a new tab on middle mouse click.
A new tab is not identical to a new window, but does mean you don't lose your place on the HN page just because you clicked a link.