Project Management Software

Hi
I'm looking for some software (either cheap or free) to manage web projects. It can be a hosted solution or a download-and-host-yourself deal (if it's in PHP/MySQL).
It needs to have support for client logins and needs to be simplistic and professional.
Can anyone point me in the right direction? I've already Google'd around, but I'd like some third party opinions.
Cheers

See original post by dylanj