I just received my bulb and ballast from www.1000bulbs.com and I could not be happier. The bulb is so bright it's just insane. Also the ballast is very quiet. I have heard other people state that some ballasts give out an annoying hum or buzz. I sure am happy this one is so quiet. Also this ballast is fairly cool for a coil and cap ballast. I have had it lit for over two hours now and I can still put my hand on it. 1000bulbs.com also shipped the order really quick as well with really good packaging.

My ballast hums, but only while the bulb is warming up. Once the bulb is warm, its silient

I got the 400w 120v ballast off 1000bulbs.com and it makes a humming noise, but its so quiet I seriously doubt it can be heard when its fully inside the enclosure. Just wondering what exact bulb did you get? I took a chance and got the PLUS Import T15 26$ bulb. I looked at the USHIO they had but decided against it considering, its only about 42+shipping but I'll try my cheapy then upgrade.

The bulb I ordered from 1000bulbs .com was catalog code: MH/04002P
it is listed as 400 Watt - ED28 Reduced Envelope - Metal Halide - M400/ED28/U
The description is as follows.
This is a Long Life, Bright White, High Efficacy, Metal Halide Lamp With a Color Rendering Index of 65. This Specialty Lamp Appears Whiter Than G.E., Philips and Sylvania. This Lamp Blows Away Any Other Bulb on the Parking Lot, Warehouse or Ball Field with exception of our Exclucive EYE Brand.
Quality Spec Brand
400 Watt
Clear
Metal Halide
Reduced Envelope
ED28
Universal Burning Position

The ballast I bought is a multi tap ballast catalog code: BS/MH0400MT

I also bought the mogul base from them as well.
It's a great setup I can't wait to see it inside my projector.