Here's an article from Microsoft MVP John Barnett (who says that he's tried this method):
http://vistasupport.mvps.org/repair_a_vist...e_vista_dvd.htm
It differs from your Microsoft instructions - but I suspect that the Microsoft instructions may have more stuff buried inside of them. Would it be possible for you to post the complete instructions from the email?
Memtest and other similar applications (like the Windows Memory Tester) basically search your motherboard for memory to test. In doing so, they've got to make some assumptions about how the memory behaves (and how the motherboard chipset supports it). Depending on this, the 4gB of addressable memory may not be able to be seen - so the only way to tell for your particular system is to try it.
As an option, I can send you a copy of the memtest.exe from my 64 bit system (it's only 384 kB in size) and you can put it in your Boot folder to see if it works for you. If you're interested, send me a PM with your email address and I'll send it off to you. DON'T POST YOUR EMAIL ADDRESS HERE!!!
Memory amounts of 4 gB and above are still a rarity in the computer world - so you're going to find spotty support for it everywhere. Let me know what you'd like to do.