avoiding vga all together is ideal. digital connection to digital connection is the way to go. so if your monitors have dvi, hdmi or displayport use it. but if vga is all you have than you need "active displayport to vga adapters". active being the key word.
You do realize that all displayport to vga adapters actively convert the signal from digital to analog right?
your clearly not familiar with what active and passive means on display port adapters.
ill explain from the beginning.
Eyefinity requires an ACTIVE adapter to enable a third monitor on HD 5000 cards or higher. Passive will NOT work, except for two monitors on a triple setup or the first two monitors on the eyefinity 5 and eyefinity 6 cards. For the other three/four monitors, active is still required. A quick explanation of why is because DVI/HDMI requires a special clock, which the card is only able to provide two of. Displayport does not use this clock, so ATI used it as a workaround.
An active adapter converts a true displayport signal into DVI/HDMI/VGA/whatever else. It will have either a converter chip or a DAC built in to do said conversion.
Passive adapters are merely a cable to go from displayport to DVI/HDMI/VGA/w.e. The video card detects the monitor as such, and outputs the required signal (DVI/HDMI/VGA). This does require one of the two aformentioned clocks, hence why they do not work with eyefinity cards.
Active adapters, on the other hand recieve a displayport signal from the video card, and convert it to DVI/HDMI/VGA. They will always have some sort of onboard DAC or video converter chip which they use to convert the dp signal. Lately, most everyone has been referring the DAC ones (which are the converters that go DP->VGA) as 'passive.' This is not the case.
I am aware of what active and passive adapters are. Maybe I should have elaborated in my OP. I am looking for the most economical solution(please don't suggest a DV to dual link DVI adapter which requires external power via USB).
DP to VGA active adapters run $10-30 and DP to single link DVI seem to be a minimum of $30.
My current setup with nVidia is with a card that has a DVI, HDMI, and VGA connector and there is no discernible difference in quality at 1080P between the three screens. My monitors have connections for all three inputs (DVI, HDMI, and VGA) so I hold no reservations towards any single connector. Nonetheless, I am unsure why you would shun VGA as a viable output for 1080P.
The DP to DVI adapters no longer need USB power and I would avoid the ones that do. Those were the first generation adapters which were always problematic. Current adapters DO NOT require a USB plug. My adapter that did require the USB plug all of a sudden stopped working within 2 months of the newer type of plugs (that ATI endorsed) coming out. (Yet if I rolled back to a previous driver the adapter worked again).