By Aidan Malley

Published: 06:40 PM EST

While Apple may not have had the strongest of holiday sales for Macs and iPods, estimates for sales of iPhone 3G versus T-Mobile's G1 may show Apple's device having outsold one of its closest competitors by a ratio of six to one in the US alone.

Morgan Stanley has issued both research notes and a survey ahead of Apple's quarterly results report that paint a mixed picture for the Cupertino-based electronics maker, but which show the iPhone as favorable all the same.

Based on polls of recent cellphone buyers, the analyst firm believes T-Mobile USA may have sold upwards of 300,000 of its touchscreen G1 handsets from launch in late October through to the end of 2008. In contrast, even Morgan Stanley's prediction of about 1.75 million iPhone 3G units sold through AT&T is about 5.9 times greater than what T-Mobile is believed to have managed.

A number of factors play into the wide gap between the two. Apple's handset had the full run of the quarter as well as significantly longer time to establish its reputation. AT&T also counts a significantly larger subscriber base as well as a much more established 3G data network to encourage sales. T-Mobile's faster data speeds reached only 25 major coverage areas by the end of the year versus over 300 for its challenger.

Worldwide figures aren't mentioned in the survey, though Apple's advantage widens here with over 70 countries selling iPhones where only the UK could sell the G1 outside of the US.

And outside of the cellular industry, Morgan Stanley analyst Kathryn Huberty cautions that Apple is liable to show relatively disappointing though not catastrophic performance. Apple's Mac sales are estimated to have grown 4 percent year-over-year in December, which is strong in a weak economy but significantly below the 10 percent predicted for the PC business as a whole.

In a consolation to Apple, Huberty notes that Hewlett-Packard fared worse and watched its sales slide 5 percent versus the same month in 2007. The Mac's creator also saw its inventory levels drop to as little as three days where many others' accumulated as customers held off on purchases.

iPod sales are also forecast as partly contradictory. Sales in December may have dropped 9 percent compared to the year before but may still have resulted in a slight market share gain to 71 percent of the entire US market.