That's for the GeForce4 MX 64MB, mine is GeForce4 MX 32MB and therein lies the uncertainty.
What does the System Profiler report for the VRAM of the card?
I have a Geforce4 MX from a Quicksilver, and as far as I know, the Geforce4 MX in the QS series are all 64MB VRAM.
Does the card have DVI and ADC or VGA and ADC ports?
I bought this Quicksilver used some years back and it appears the original owner had specified/installed the GeForce4 MX 32MB card which I believe was available as an option on some G4s later than the 733.
If the card came from a MDD, then it would be the Geforce4 MX 32MB card.
http://support.apple.com/kb/SP63
I did find one spec which suggested it would support dual monitors as in my OP but it was not wholly clear.
PC or Mac, the Geforce4 series all support dual displays.
Does the existence of a second display slot in System Profiler indicate dual monitor capability or is it always there regardless of card?
If dual displays were not supported, the System profiler would indicate that.
As you can see from the MDD technical specs page linked above, dual displays are supported.