I took my problem to nVidia live chat (yes there's such an animal if you haven't stumbled on it yet), and asked why I can't get dualview on GT 220 that came with Dell's Studio 435T, 64bit Win7. At first the chat led me through different drivers to no avail, and then, now, confides that that feature is "not available due to the limitations of Windows 7" compared to Win XP!
I barely escaped a gag to hear -- The hyped all-powerful Win7 is falling short of its old self two generations back.
Has anyone put this question to MS to hear their reply or excuse or a charge back at nV?
Win7+p does not give Dualview (with "Autodetect" checked off), which sends streaming video or the DVD output to the secondary display in full screen, without interfering with the primary monitor for normal computing like Net surfing.