various OS memory usage by VirtualBox recomendations

[Vitorio Okio]

Playing with VirtualBox 3.0.10 I've made a curios observation about 
recommended Base Memory size in MB for various guest OS:


IBM OS/2		- 48 to 96 for different incarnations

BSD 			- 64 to 128 for different incarnations

Windows XP 		- 192 (twice less of Ubuntu is a surprise to me)

Debian, Arch Linux, 
openSUSE, Fedora, 
Gentoo, Mandriva, 
Red Hut, Xandros,
and other Linux 	- 256

Ubuntu, Turbolinux 	- 384

Windows Vista & 7 	- 512 (I would be surprised these not to loose).

Are these numbers really suggestive or their are subjective to VirtualBox?

Sincerely I was the most surprised of the Windows XP biting all Linux 
distros, as well by the fact that Ubuntu looses quite significantly to 
all other distros.