I just added a GeForce 6200LE.
When I booted up I got a bunch of error messages, and had to reconfigure X. I went into recovery mode from Grub and typed:
sudo dpkg -reconfigure xserver-xorg
I installed the Linux genetic nv driver and was able to bring up mint.
This gives functionality, but to get 3D effects and fully utilize the graphics features, you must install the non-free nVidia drivers. Running Envy should install the correct nVidia driver.
Btw, Newegg has an EVGA GeForce 6200LE 128 MB AGP for $34.99 and the 7200GS 512MB (128 on board) PCI Express x16 for the same price.