Needham’s Charlie Wolf found lots of good news for Apple (AAPL) in IDC’s report on the state of the worldwide PC market for Q3 2010.

That’s because his report to clients issued Tuesday never mentioned that the Mac’s share of that market last quarter was only 4.36%.

Instead Wolf focused exclusively on the Mac’s rate of growth.

Viewed that way, Apple is cleaning Microsoft (MSFT) Windows’ clock. Wolf’s bullet points:

• At 28.5%, Mac shipment growth in the September quarter easily outpaced the PC’s market growth rate of 9.7%.
• The twin drivers of the Mac’s outperformance were the home and business markets. Mac shipments grew 25.3% in the home market compared with a market growth rate of 10.4%. More significantly, the Mac became the dollar share leader in the U.S. home market with a 29.4% dollar share.
• Continuing the pattern first observed in June, Mac shipments in the business market increased 66.3% compared with just 8.5% shipment growth in the business market overall. Only time will tell whether these data points represent the canary in the coalmine.
• Notwithstanding its premium prices compared with Windows PCs, the Mac should continue to growth faster than the overall PC market, propelled by the multiple halo effects now emanating from the iPod, iPhone and iPad.

That second point, about the Mac grabbing the dollar share lead in the U.S. home market — apparently for the first time since the Apple II — would sound more impressive were it not for this footnote:

“It should be noted,” Wolf writes, “that the increase in the Mac’s dollar share of the U.S. home market resulted chiefly from IDC’s estimate of a sharp increase in the average price of a Mac sold in this market. This increase was different from the average selling price of a Mac Apple reported for the September quarter, which was about flat with June. However, in an email response, IDC stood by its average selling price estimate. If Apple’s average selling price were substituted for IDC’s, the Mac’s dollar share of the U.S. home market would fall to 20.0%, slightly less than HP’s share.”

Below: Wolf spreadsheets showing the Mac’s sales growth by market segment and region.

[Follow Philip Elmer-DeWitt on Twitter @philiped]