How to temporary disable nvidia driver

[George Bak]

Hi!

I'm creating Wheezy bootable USB.
Installed nvidia driver on it:

aptitude install nvidia-glx nvidia-kernel-686-pae

I'm trying to find a way to start X on a machine with
Intel or ATI cards without removing nvidia drivers from disk.

The idea is to make my personal portable USB Flash
capable to work on any of notebooks in home/office/travel.

How to do it Debian-way? Or where to read about?

Thank you.