if not, just call the page like this...
<a href="your_page.htm" target="_new">click here</a>
Server side script is not event driven. It is executed when the page is loaded.
What Dave said.
There may be no actual "_new" target, but the way browsers work is that you can add any name there - as if referencing a frame even, and if the name is in use, it'll open it in a new window, thus making target="_new" a perfectly viable way to open a new window ;)
Yes, the syntax is not by the book, but it works :D