I was unable to find info from anyone who learned to live quietly with the G4-VGA, so I'm taking a stab at it myself. In addition to quieting the VGA cooler, I'm looking to slow down my rear chassis fan to a quieter speed.
Around April I got an Asus V8420S, one of the Geforce Ti4200 cards built onto a 4600 PCB, using faster than the stock RAM (3.3ns I think). I don't know if it's just an Asus thing or what, but the stock fan was a piece of poo. It started to make bearing noises into the second week of use, so rather than wait for a failure I replaced the whole cooler with a G4-VGA. I was very happy with this solution until a couple of weeks ago, when the noise level finally started to get to me.
Today I removed the fan and the clear plastic guard from the heatsink, and rigged an 80mm Antec fan on an old PCI slot cover to blow from the bottom of the case onto the heatsink. Since the AGP card is the only one in the system, I had plenty of room to play with this. After a few runs of 3DMark, I don't see any problems with graphics or with the heatsink being hot to touch. The Thermaltake is listed at 10.4 CFM, so a 12v 80mm ought to be way overkill. Also, the hub of the G4 fan sits almost directly over the core itself, so it can't have been doing that great a job.
Now that the tiny screamer fan is gone, I can hear 80mm fans and my hard drives, which I knew I would. I have a Zalman MFC1 on the way to take care of the fans - we'll see how happy I am with the noise level at that point. The PS is an Antec SL400, and seems to be the quietest part of the system, so I'm not worried about that. I have a Dell here for side by side testing, so the bar is pretty high.