Load simulation tests

Hi all,

I was wondering if there were any ways to simulate loads on a PHP script
running on the server? Basically, I'd just like to take one of my sites
through a dry-run so to speak and simulate x number of visitors.
Ideally, I'd prefer something that didn't have to be installed on the
remote server. Also, it would have to be something I could use from
within Linux, as I only have Windows running as a VM, and I'm not sure
it would work as intended if run though a VM.

Have any of you used such tools, and if so, are there any you'd
recommend?

Thanks,
Ash
http://www.ashleysheridan.co.uk