What happen is that after a few support emails from nvidia, I failed to get their solution to work. They suggested a couple of older drivers that didn't show the hi-res modes. I seem to have fixed it by uninstalling nvidia display drivers in safe mode, rebooting into safe mode, cleaning nvidia display drivers with Driver Sweeper, rebooting normally, letting Vista setup the default vga driver, then installing one of the latest drivers, 177.83. This is the first driver that seems to cause my legacy monitor to be detected as generic non-pnp display, not as "viewsonic p815", which is good (I think vista is playing monitor nanny with the P815 and does the 'favor' of returning to the 1600 x 1200 mode.) The hi-res modes are there and working now (unchecking "hide modes..." box is normal procedure and hardly needs mentioning anymore). I thought I had a solution with 177.79 but the hi-res settings did not survive a reboot -- I lost the hi-res modes just by rebooting. The 177.83 driver
is working so far but I am only 1 day into it. It works with my hdtv in clone mode also and has fixed a few problems with that as well. If the settings hold as they are now I am happy camper.
I tried tweaking a new .inf file for the viewsonic p815 with PowerStrip, setting the higher modes, but that didn't work for me.