But then you wouldnt get support ;)
M$ like any other business discontinues products to make people move up a notch making them more money, Windows 7 is what Vista should have been, as W7 is based on Vista they are not too dissimilar, but I still prefer Vista, preference really as I prefer Server 2003 to 2008.
Newer is not always better but XP is long past its sell by date, its only the most used OS due to corporate compatibility with servers :)