Installing graphics card driver, causes system to collapse

Hi, my problem is thus:

I recently installed Ubuntu 10.10, and I've got it mostly working. The one thing that is not working as should is my graphics card. It is a geforce Nvidia 425m. I'm using a sony vaio that previously ran windows 7 64bit. My screen resolution won't go past 800x600 which is very low and very annoying as it distorts everything. When I first start up Ubuntu it updates as should(roughly a 300mb update). I reboot and everything works fine. The problem comes when I log back in. I go into administration>additional drivers to download and install the correct geforce driver. It pulls the proprietary driver, which i hope is the right one and says this:

{
NVIDIA accelerated graphics driver (version current) [recommended]
Tested by the Ubuntu developers
License: Proprietary
3D-accelerated proprietary graphics driver for NVIDIA cards.
This driver is required to fully utilise the 3D potential of NVIDIA graphics cards, as well as provide 2D acceleration of newer cards.
If you wish to enable desktop effects, this driver is required.
If this driver is not enabled, you will not be able to enable desktop effects and will not be able to run software that requires 3D acceleration, such as some games.
}

When I install the graphics driver, though, what happens is it tells me I will have to reboot for it to take effect. Here's the main problem: when i reboot and the system restarts it won't actually begin to run. I see Ubuntu 10.10 on a purple background for about 3 seconds then the full screen goes blank and it's just purple. At this point there's no way to start the system and I can't even run any commands. My only solution is to pull back out my install cd, wipe the hard drive, and re-install. This has happened 4 times since yesterday, and each time I've had to re-install Ubuntu and start completely over.

Please, if anyone has had such a problem or heard of it before, tell me how to solve it. I'm really wanting to begin to use linux, and really at this point there's no going back to windows because I don't have the install disk. I just want my computer to run right so I can begin to work! Please help!

Thank you for your time!