1 GB is twice what MS says it needs. Of course lets look at the problem of a non-server OS that the maker admits needs half a gig of RAM.
Being the minimum for what it takes to run and being what it takes to run good is two different things, if going by your premise then the XP box should have had 512mb of ram instead of the 1 gig, which would have been twice what XP’s minimum requirements were.