Overall desktop sales in February rose by 30% in units and 33% in dollars, compare to the same period a year ago, according to a new data from market research firm The NPD Group’s Retail Tracking Service.

The firm said that February marks the third time in the last four months that desktop revenue grew faster than notebooks, and the fifth consecutive month of desktop revenue and unit increases. The average selling prices climbed almost 3% from February 2009 to $670 and were far above the notebook/netbook ASP of $602.

According to NPD, the Windows desktops saw a 15% rise in units and an 8% increase in dollars over the four months since Windows 7 launched. While the increase is modest, it is a positive trend considering that prior to the introduction of Windows 7 desktop sales declined 21 out of 22 months.

Stephen Baker, vice president of industry analysis at NPD, said: “Desktops have been the surprise consumer technology growth category of 2010. Desktop growth has come from both PCs and Macs. 

“Windows 7 has been propelling the PC side of the market where desktop ASPs have been higher than notebook/netbook ASPs in three of the last four months. We are also seeing tremendous growth numbers from the iMac after a few lackluster quarters from Apple.”