Debian IS huge.
3DVDs are just the tip of the iceberg. Debian supports Arm, Mips, x86-64, and a whole bunch of other types of systems. 11 different types of computers are officially supported.
Almost all the software supported in x86 is supported on other systems. Also you have all the source code for all of that also.
So your looking at probably 40-50 different DVDs for the entire stable release. Then on top of that you have old stable, testing, and unstable and a large number of unofficially supported archetectures and variantes like FreeBSD-based Debian.
Its the largest distribution out there, plus it has some of the best quality control and is very very complete.
They are very politically oriented towards 'software freedom' so it turns a lot of people off.
Check out the Debian Installation manual:
http://www.debian.org/releases/stable/installmanual
If you want to install Debian the best way would be to download the netinstall cdrom image. This is a minimal installation cdrom that will download the software you need from FTP sites. So you want to use it if you have a fast internet connection. That way you only downlod the software you want which will be a tiny fraction of everything Debian supports.
Also if you get comfortable with Debian and want newer versions of the software then Debian Stable offers you can always upgrade to testing or unstable and get newer versions of everything. The downsides are that upgrades are going to be much larger and you'll have to deal with broken packages and more bugs time to time.
The video card support is up to Nvidia, not any Linux distribution. Their drivers are closed source and have restrictive licenses so that you are stuck waiting for them to support your video card.
Debian will offer nvidia drivers through their non-free repositories, but you probably won't want those on such a new video card.
So what you will have to do is is compile and install the drivers from Nvidia's installation script.
WARNING:
*** These will make your system incompatable with Debian-provided nvidia propriatory driver packages. Also if you upgrade portions of X or upgrade your Linux kernel you will break your drivers and they will have to be reinstalled. ****
To install the propriatory nvidia drivers from nvidia's executable you have to go:
apt-get install module-assistant
m-a update
m-a prepare
Goto Nvidia's website and download the latest driver installer. Also you need to do this while logged in from the virtual terminal.
So after downloading the package, put it in /home/username
Log out of the desktop. Switch to the virtual terminal by going ctrl-alt-F1
Log in as root.
Stop GDM by going:
/etc/init.d/gdm stop
Then run the Nvidia installer.
chmod +x NVIDIA-Linux-x86-1.0-9755-pkg1.run
./Nvidia-Linux-x86-1.0-9755-pkg1.run
You can autocomplete file names with the tab button by hitting it a couple times.
When the drivers are finished installing they will offer to reconfigure your xorg.conf, let them, and then start up gdm. You should see the nvidia icon. Also it should install some nvidia utilities for configuring dual monitor setup and such things.
/etc/init.d/gdm restart
Then log in, and then run the nvidia stuff to get your dual monitor setup.
Hope it works for you.