The NPD Group says that Mac sales increased 35% in May and expects that Apple will sell 3.1 to 3.2 million Macs in the June quarter. That’s year-over-year unit growth of 19 to 23% — better than Wall Street’s consensus of 19% year-over-year.

Piper Jaffray analyst Gene Munster says the NPD data shows little cannibalization of Mac sales from the hot iPad. However, iPod sales are down 13% year-over-year, which is a decrease greater than the 9% Munster had forecast. Still, considering that the iPad has an average selling price four times higher than the iPod, the analyst sees it as an overall positive for Apple.