@drmike
As an IT Manager for a specialized hosting provider, I *report* anyone performing unauthorized vulnerability scans or stress tests of any of my systems - and have filed legal actions in some cases. NEVER scan or test anyone's system other than your own, or without prior written authorization to do so. These stipulations usually fall within the AUP of your ISP or VPS provider and can get you canceled quite quickly.
The goal of a good server stress test tool is to find the point where your servers stops performing effectively. As the admin of LEB can attest, that turns into a DoS attack.
@supermanhosting.com
Assuming you have access to a linux box already, use a combination of MTR (Matt's Traceroute) and any download test files a provider makes available. However, like @admin mentioned, that won't tell you a damn thing about the performance of the host.