Do you necessarily need Windows 7 Ultimate to run <16GB RAM?

Windows 7 home premium will support up to 16gb of ram.

http://msdn.microsoft.com/en-us/library/aa366778(v=vs.85).aspx

Any windows 64bit operating system will run more than 4gb of ram 8 ,12 ,16 ,24 ,32. I used to run 24gb of ram with windows XP 64BIT.

hi, quick question, i figured i might as well popst here insted of starting a new thread on the same topic. does it matter what computer/ make model you have, or all are fully supported up to IE 16Gb ram?
further specs if needed
compaq presario cq5600y narra5 amd athlon x4 640 two ram slots, 2gb installed. running win 7 X64 home premium. it states also, on HP's site that win 7 x64 will address 8-16Gb ram. i would like to just verify with some other people as well, and it seems your a good person to ask   thank you

Not exactly,
Don't know about XP 64 bit, but for windows 7 64 bit the software support is:

Home basic 8gb
home premium 16gb
professional and higher 192gb.

From a hardware point of view, it depends on the motherboard.

Current generation motherboards will support 8gb ram sticks, up to the maximum number of ram slots installed on the motherboard.
Some motherboards may only support 4gb ram sticks.

my MB states that it supports dual 2gb 4gb 3.3 usable on win 32bit home premium win 7, do you think it would allow dual 4gb sticks, since i have win 7 premium x64 bit? HP doesnt exactly offer much services for advice i notice

3.3gb usable is normal with a 32 bit os.

I think you would be ok with a 8gb kit of 2 x 4gb sticks.

One way to check would be to go to a ram website, like kingston and access their ram configurator or upgrade configurator.
Most ram vendors have such an app.

Enter your pc or motherboard, model, and you should get a list of compatible kits. If you should ever have a problem, this is some assurance that you won't get finger pointing between the mobo and ram vendors.

ah, okay thanks for the help. ill take a look around online, this system states it MUST or actually "ONLY" unbuffered non-eec ram. ill do as your suggested above with the model # and -ram kit-