web design mockup software

hi i would like to make a quick set of designs to visualise the look and user interface of a new system, both for the client's benefit and also for me to have a clear idea of what i am aiming at, what is a good software to do this? thanks

 

I use illustrator
it's not free OR cheap
but if it's for business
I'd say it's worth the investment


vanessa.

 

corel draw would do the job too - it's just about habit...

 

i used to use flash for that, now loving adobe flex - where you can drag and drop interface. But is only suitable for system type of morkup aint free tho.

 

Inkscape is a bit like those programs mentioned and it's free... I'm sure it's no where near as good though.