You apparently are still running XFree86-4.3 rather than upgrading to xorg-x11 for your X server... first I would suggest you do this upgrade, more information about it can be found on the fedora test mailing list.
Your current config has only one monitor and device configured, this is a single monitor setup all the way. To get started you should use the config tool, system-config-display
, which has the ability to configure dual head setups. If you don't have it installed, get it! (from Fedora rawhide)
I have attached a sample of a dual head setup created by this tool. The config will show you the basic building blocks behind a dual setup.... but I have not used it, so it is nothing more than an example (I have only one monitor atm).
And finally, you are using the "nv" driver, which is capable of doing nothing more than 2D, and displaying software rendered 3D. If you wish to use 3D acceleration you'll need nVIDIA's driver which you can download from www.nvidia.com
, or get RPMs from links in my sig (I suggest the latter... the reason they are in there).
btw, what I've described here is 'dual head' operation rather than 'TwinView'... the latter of which you should install nVIDIA's driver for, and then review their latest readme (Appendix I) here