A new study by NPD Group revealed that about 47.7% of desktop sold at US retail shops in October, was iMacs, Mac minis or Mac Pros, an increase from 45% in April and a sharp surge from just 33% in October 2008. Mac notebooks also saw a sequential gain from 30% in April to 34% last month, though this was a drop from 38% a year earlier. The release of new iMacs on Oct 20th is likely to have given Apple a boost to its numbers, NPD industry analysis VP Stephen Baker noted. At the same time, Microsoft’s own launch of Windows 7 just two days later triggered its own increase as customers waiting for OS upgrade purchased their systems. Apple’s higher notebook performance last year was helped by launch of then-new unibody MacBooks and MacBook Pros. The average cost of a Mac desktop in October was $1,338, or 2.7 times the $491 for a typical Windows tower. A Mac notebook on average cost $1,410 versus $519 for common Windows pricing.