I've got Win7 pro 64bit on my laptop for 3 months now.
My gpu has it's own 512DDR memory and can take up to 3GB from my system.
I have 8GB RAM never had a problem. I have never seen it above 30% usage normal use (because with Maya, Fusion, photoshop, AfterEffect, Compustion and HD content, that i am working with, RAM is never enough!!).
I only had 1 problem but I gues it's a firefox issue or a bug.
Whenever i leave firefox open for many hours downloading from rapidshare constantly i see my ram usage growing hour by hour. But again after 54hours of continuous dowloading i saw my RAM maxed out and my system lagging and it was keep lagging until i reboot!
Right now with
Firefox (10 tabs with a flash game opened and jave loaded),
uTorrent (with 30 torrents active),
gmail notifier,
Eset firewall and antivirus,
all my drivers (sound, wacom tablet, webcam, touch pad, touch buttons), 2-3 gadgets
magicISO and all the effects loaded.
It's on 19% with 1.53GB used and 6.5 available!!!
The same system with Vista 64bit was always between 1.6GB after a cold start and at 2.5/2.8GB with the apps I running right now!!!!
So I find this article at least useless. they put apples and oranges together.
1.5GB for a 64bit OS it not a lot. If you consider that it uses a lot of 32bit apps that apparently due to the emulation consume more ram (like u Torrent it never goes over 10MB in 32bit OSes but right now it is using me 21MB same for firefox it's using 160MB with 10 tabs when the same version takes 100MB with 15tabs).
So the answer to this article is YES win7 PC's max out ram the same way that 10years ago a PentiumIII with 128MB RAM was maxed out running winXP instead of win98!!!!