I am doing work for a smaller company, and we need to load test our system with anywhere from 200-500 concurrent users. All software I've seen regarding load and performance testing has quite a price on it. Open source tools seem to be mostly linux based. We are all running Windows machines. from what I can understand, all it needs to handle is straight HTML, and SOAP. Any suggestions?
Load testing costs quite a bit, because accurate testing requires an array of virtual machines and a large internet pipe with a locally throttled networking layout.
What many companies do these days is create a Beta testing system where they have several thousand users sign up for a free Beta testing account and are required to use the site at certain times with the assumption that the site could have problems or shut down at any time.
Another option might be to get the $50/day test from LoadImpact.com and run it for a week or so.