For low noise you want to aim for low power consumption. For that I would recommend an i3-2100 based build since it's only 65W and it gives nice performance for the price.
i3-2100 - $124.99
Low power and hyperthreading, both good for your uses.
8GB G.Skill Ripjaws X - $29.99
This is incredibly cheap and may come in handy.
ASRock H61DE/S3 - $67.99
ASRock are pretty decent and an ATX board is fairly rare at this price. has plenty of USB ports and video inputs as well as SATA 3. HD graphics supports dual display too so having enough video inputs on the motherboard is important.
Intel 320 Series 40GB SSD - $94.99
Possibly a controversial choice since it's quite expensive and SATA II but Intel make some very nice SSD's, don't let the numbers fool you. An SSD should make the whole system feel that bit snappier and may help a lot.
Seagate Barracuda 250GB - $89.99
Hard drives are expensive at the moment so I wouldn't shell out for more than this personally.
Antec Earthwatts 380W - $44.99
Excellent PSU for the price and plenty of power for this build even if you add a low end graphics card for whatever reason.
Antec VSK-2000 - $44.99
No need to spend any more really for this type of build.
Total - $497.93 before rebates and shipping
I realise that's perilously close to $500 but it should suit you nicely.
Thoughts: The system will serve me very well for probably 5 years, and then I can overclock (will need a cpu cooler) the i5, or move up to an i7. On chip graphics are fine for me. I'll probably wait until hard drive prices drop before pulling the trigger.
Question: You said HD graphics supports 2 monitors. Can I drive 2 monitors off this mobo as-is, or will I need a graphics card?
I don't think that's actually going to seem any faster to be honest and by the time it's not useful for relatively basic tasks I don't think the i5 will make much difference to be honest. It's up to you though of course.
You should be able to run 2 monitors from the mobo as is with Intel HD. Just make sure to install the drivers and enable it in the BIOS.