stravis, the only thing that uses more RAM in x64 is a program thats 64bit. If you have 32bit, you can't even use all 4GB due to it also having to have room for the GPU memory. But if you run a 32bit program on 7 x64, its still like 32bit and uses the same amount of memory as it would on 7 x86.
As for the report, I have 3 tabs in IE 8 open, Firefox and the launcher for STO and I am running at 40% of 4GB so about 1.6GB. When I had Vista, it was about 50%.
Now the biggest part he is talking about is the caching system, aka SuperFetch, that Vista and 7 have where XP does not. It will take your unused memory and cache frequently used programs so they will launch faster.
Some people think its using it always, but if you have a program or your system needs more memory Vista/7 will free up the memory it needs by unloading the cached programs.
So in the end, its all just opinion. I haven't noticed any slow downs in 7 and its been much faster than XP and Vista. I think the guy needs to read up on SuperFetch a bit more before posting claims like this.