Starting with PCs, U.S. retail sales of Apple of Apple’s desktop Macs slipped 1% last month over the previous year. At the same time, PCs sales increased 2%. The message on the wall here is that American consumers are going down-market for their computers – scooping up the commodity low-margin models that eat away at the corporate bottom line.

Given that Apple’s slowdown comes during the ramp-up for holiday sales, the projections for early 2009, and perhaps the entire year, are expected to look dismal for its Mac family of desktops.

It seems that during hard times, consumers are willing to forego Apple’s premium pricing strategy in favor of stripped-down models that still provide basic functionality.

The market slump for Macs hit fast and hard. It was only the previous month, October, which shipments had surged 28% from the year before. That dramatic reversal indicates a panic mentality among consumers, which could in fact take all of next year to overcome.

The shift in buying trends not only hurts the manufacturers but the retailers as well.

Yesterday, Best Buy Co. (NYSE:BBY) said it would reduce capital spending and offer buyouts to corporate employees. The electronics retailer posted a 77% drop in quarterly profit over the same period a year ago.

Slashing capital expenditures by 50% next year primarily means that the company would open fewer stores – further eroding revenue projections.

The news was even worse at competitor Circuit City Stores, which filed for bankruptcy last month.

Naturally, semiconductor companies which supply the components to all these products would be hit as well. Unfortunately, even these experts at market predictions got blind-sided by the sudden reversal.

Just as Apple’s Mac sales dropped some 29% in the period of a month, semiconductor revenues hit the skids much faster and longer than originally anticipated.

Worldwide chips sales are expected to decline 16% next year, resulting in the industry’s first-ever two-year sales slide, said research firm Gartner Inc.

The 16% pull back represents a higher revised number from Gartner, which had predicted a drop of 2.2% only last month.

Overall, 2009 is clearly not the year to dive into tech. Even value investing can be precarious right now with no relief in sight for more jobs, more credit and more demand. While this can be a frustrating period for tech investors, it’s much better to sit on the sidelines than stand in a bread line.

These countries whose communications systems have suffered from decades of neglect and under-investment could never match the needs of a fast-growing economy. So rather than wait for the government to lay cables, consumers instead opt for instant communications via cell phones.

Now a new report from market-research firm Gartner, Inc. says that cell-phone sales in emerging markets will hit a wall. Investors should take this information to mean that these markets will continue to be soft through 2009.

In Q3 2008, about 309 million mobile phones were sold world-wide, Gartner said – a 6% rise from a year earlier, but a sharp drop from the 16% year-to-year growth seen in the Q3 2007.

The Asia-Pacific region, once a hotbed of cell-phone sales, is expected to stop dead in its tracks, according to Gartner.

This is in stark contrast to earlier numbers from Gartner, which showed that Q1 2008 Asian cell-phone sales jumped 26.6% from the same quarter in 2007, driven by demand in India and South Korea.

What does this mean in terms of economic growth?

Research shows that greater cell-phone usage can stimulate economic growth in emerging economies. Based on market research in China, India and the Philippines, consulting firm McKinsey & Co. found that raising wireless penetration by 10 percentage points can lead to an increase in gross domestic product of about 0.5%, or around $12 billion for an economy the size of China.

So armed with this new data, we recommend that investors say clear of emerging markets at through Q2 2009 or maybe longer.