S.B, our customers are installers, so he doesn't work too much on a PC, they go to the sites, take the dimensions, and then the scans to send them to us.
GT22, I found my happiness on your site, but 180$...^^ A bit expensive for me...
Lucas, with Inkscape it almost works, but I mostly have a problem with the scale...
It's OK for autotrace guys, I didn't have it enabled.
As for the precision, it's not there yet....
I think that for the first time, my client should give me a dxf or a dwg, because there will always be a gap between what he wants, and what I'm going to draw...
Thank you all for your advice.
As for the best answer, I'm still trying to choose which of you answered better^^ =)