XP is 10 years old and like DOS was 10 years before XP, so is XP now to 7.
drivers will slowly fall to thbe way side for XP and XP is now the red headed step child and is getting sub-standard drive support.
7 scales better and on average, newer computers use ~15% less power in 7 than XP.
7 scales better than XP for multi-cores. 7 has had about 1/4 the amount of exploits/bug found than XP did in the same time frame.