[help!] Can not use nvidia driver in debian sid

[iijima yoshino <iijimayoshino@gmail.com>]

Hey, there!
I have an old pc with a Nvidia GeForce 6600 card.
Firstly I installed Debian 7.4 and everything was O.K.
(nvidia-detect told me to install nvidia-glx and it worked.)

Then I changed a monitor and upgraded to Debian sid.
(old one is 1024x768, the new one is 1280x1024.)
And nvidia-detect tells that the nvidia-legacy-304xx-driver is
recommaned.
I reinstalled the driver and used nvidia-xconfig to
creat /etc/X11/xorg.conf

Rebooting ....

lsmod |grep nvidia, not found?
startx, no screen found, what?
After tried several times, like modifing xorg.conf, using xrandar,
whaterver.
I decided to use the nouveau driver, but the screen is only 1024x768.
So I'm lost now, why a monitor-change can make this happens?
Please help! And thanks for any helpful advices.