Yes, 1GiB should be the lowest minimum for today's demanding needs, even for Linux based OS's. And even with that, try having a few browser pages open, have VLC open to listen to music, or better than that, try running XBMC. Sure it'll run, but give it more RAM, it'll run better. Even the low end PC's of today, many ships with 6GiB of DDR3 RAM, running at 1600MHz. This is for a $348 PC, just seen one in the store yesterday.
I'd say 1GiB for basic use, such as Web browsing, checking email, but the good apps will suffer. On a 32 bit PC, 2GiB, 64 bit, 4GiB. That will get most things done on the Linux based OS. If one intends of running virtual machines, more may be needed to get the most out of the VM, while not risking leaving too little for the main (host) OS.
- 700 MHz processor (about Intel Celeron or better)
I have to question this one, as I haven't seen this low of a CPU since the turn of the century 3 & a half months shy of 15 years ago. Maybe on a smartphone or handheld computing device? The smallest that I have & among the smallest that I've had, in a 1.73GHz Intel Pentium M, which is a whopping 1GHz more than Ubuntu's published minimum.
What we run into here with "minimums" is the same thing that MS has done for years. Remember they said only 64MiB minimum RAM was needed (although 128MiB was recommended) & 1.5GiB was the minimum drive space? Ha! Windows Updates wouldn't fit on that space, nor could I envision XP running on 64MiB of RAM, the minimum I've ever ran & that was upgraded a week later, was 256MiB, which was increased to 1GiB & later to 2GiB (there were no 1GiB sticks at the time, as a result of this, Dell didn't know that 2GiB was the max).
A quote from the page the OP has linked:
* 1000 ΜHz processor (about Intel Celeron or better)
* 1024 MiB RAM (system memory)
* 3D Acceleration Capable Videocard with at least 256 MB
From experience, we all know that it is recommended to have 2048 MiB RAM to properly run a day to day Ubuntu.
A good start should be with minimum 1024 and recommended 2048 MiB RAM.
That seems more realistic, especially on the RAM end, though the CPU may still be the bottleneck of the system. A 256MiB GPU is also reasonable for basic use, though again, this will show if running XBMC & YouTube videos.
Most systems that were designed to run Windows 7 or later Vista models (beginning in 2008), should be quite capable of running the latest Linux based OS's. Computers that were built to run Windows XP, must have PAE & NX to run the latest releases, the last "full" Linux releases that can run on these are the Linux Mint 13 variants (MATE, Cinnamon & KDE), though Cinnamon will struggle if the graphics card is a small one. Later, a non-PAE Ubuntu 12.04 was released, but it's not a popular one, in part due to many not knowing of it's existence.