SAN FRANCISCO -- The latest numbers from Hewlett-Packard (HPQ) - Get Report and Dell (DELL) - Get Report have been key for tech investors, because both companies' quarters included the month of October, when tougher economic realities seemed to be finally acknowledged by traders.

The

Nasdaq

slid nearly 17% last month, in step with the downturn in the broader indices, as all sectors felt the ramifications of a global economic slowdown dovetailing with the credit-induced funk.

Dell's

earnings report

last week received some mild applause after the company's aggressive cost-cutting and timely stock repurchases led the PC maker to beat analysts' profit estimates by 6 cents a share, despite underperforming revenue expectations by a whopping $1 billion.

Unfortunately, Dell's weak top line looks even more unsettling in the wake of

H-P's results

on Monday.

H-P is feeling the economic pinch, but the specifics of the company's sequential sluggishness seem reasonable, given the tough economy. (Note that the company's overall revenue got a big boost in its latest quarter from its integration of its acquisition of EDS).

What doesn't bode well for Dell is the company's huge dropoff in its Mobility group revenue, which covers notebook PCs and the even smaller netbook mini-PCs. The popularity of both of these nondesktop computers is growing due to their lower costs and higher functionality.

In a recent interview with CNet, company founder and CEO Michael Dell said it's unlikely that netbooks would be a massive growth driver in the industry.

In the same interview, however, Dell also said the future growth in PCs will come from emerging markets. Look at areas where people were buying their first cell phones three years ago, he said, and that's where you'll see the growth in PCs.

Do you mean areas like the Middle East and Africa, where the research firm Gartner found "robust growth" in the sub-$500 PC segment during the third quarter?

Gartner did acknowledge it's too early to tell if netbooks are truly a new market or just cannibalizing other lower-priced systems, but the firm did say it would be tough for other vendors to make inroads on the early market grabs by Asian PC makers

Acer

and

Asus

.

This, however, is what it looks like when the demand for your products falls off a cliff:

Dell's third-quarter PC global shipment market share fell to 13.6% from 14.1% a year ago, due to struggles in the professional markets in the U.S. and the Europe/Middle East/Africa region.

None of this is to say that Dell shares weren't looking extremely cheap last Friday, when they dipped below $9. And even using the lowest analyst estimate for fiscal 2010 revenue of $55.2 billion, the stock's current price of $10.48 generates a price/sales ratio of 0.37 -- a more reasonable average valuation would put the stock's fair value at around $17 or $18 under worst-case-scenario sales.

But shares of H-P are also inexpensive -- at $33.67 they're now down about 36% from their 52-week high. And with that company's recurring revenue strength in services via its EDS purchase and its printer supplies, any future downside looks a lot more limited.