ASP.Net web stress test tool for actual use

WCAT, httperf, openload - good tools to simulate static load on the server.

I need to test actual load of an ASP.Net solution. Meaning if I'm testing 1k simultaneous users, the tool needs to log on 1k different usernames (one for each simultaneous connection) and enter 1k different strings into a textbox. On top of that the 开发者_开发技巧cookie and FORM-data (i.e. ViewState) for each connection will be unique and should be preserved.

What tools are there to do this? Free=Good

The Grinder might be worth a try - I'm not sure it can do everything you want, but it is free :)

http://grinder.sourceforge.net/