I don't have a running Ubuntu install at the moment, maybe some who has will offer up some wisdom. But, in fedora, one must add rdblacklist=nouveau and nouveau.modeset=0 to the kernel line in grub in order to stop the nouveau drivers from loading. You can't really delete the nouveau drivers because they are embedded in the kernel. What the commands in fedora do is blacklist the module so it doesn't load. I would think if you installed the drivers through Ubuntu's hardware setup, it would add the commands and module blacklists for you. I haven't used the nvidia driver for over a year now, since the advancements in nouveau perform nicely for what I need them to do.
According to this, your card should be supported:
ftp://download.nvidia.com/XFree86/Linux-x86_64/270.41.06/README/supportedchips.html
but, as stated in that list:
Some designs incorporating supported GPUs may not be compatible with the NVIDIA Linux driver: in particular, notebook and all-in-one desktop designs with switchable (hybrid) or Optimus graphics will not work if means to disable the integrated graphics in hardware are not available. Hardware designs will vary from manufacturer to manufacturer, so please consult with a system's manufacturer to determine whether that particular system is compatible.
You machine is fairly new, and might have the switchable Optimus grahics, that I don't know. What is most likely is that you borked your nvidia install, tried to remove the nvidia cruft and left some things behind, because, removing the drivers with apt-get doesn't purge all of the extras that the installation deposits.
Hopefully, one of our Ubuntu users will be along and can give you more precise help, because things have changed since I've borked my last nvidia install, and any instructions I come up with may be out of date, and hence, may make things worse.
Edit: I found this website that explains how to install the nvidia driver by downloading it directly from the nvidia website. It was done with Ubuntu 10.10, it is an alternate way of doing the installation. I also see that it tells you how to blacklist the nouveau driver in grub2 that Ubuntu uses. You may want to give it a look.
It also explains how to get into recovery mode and fix grub etc.
http://www.socialblogr.com/2010/10/how-to-install-nvidia-graphic-card-driver-on-ubuntu-10-10.html
If your not comfortable with following that how-to, and would like to wait for someone who actually runs Ubuntu to correct me or make other suggestions, just be patient. This is the weekend and things slow down here a bit on Saturday night.
Careful about one thing though. If you use grub to boot your windows7, don't remove the partition. It may also remove the bootloader for windows. Don't do anything until you know exactly what state your in. Not getting a GUI booting Ubuntu just means that your graphic drivers are borked, not your whole install. Giving us more info about how you set up your dual boot, whether your machine uses Optimus graphics and any other info you can think of, could help us zero in on a solution for you.
Now I'm just thinking/typing out loud, so I'll stop until I get some more info from you or someone else here chimes in with more help.
