This article was originally published on June 30, 2015. It was updated on Jan. 20, 2016.

The market for traditional PCs continues to decline. According to research firm Gartner, PC shipments fell 8.3% last quarter, and 8% in 2015 overall -- the fourth year in a row that PC sales have contracted.

Nevertheless, there's still a market for traditional PCs -- more than 280 million of them were shipped last year. My Foolish colleague Joe Tenebruso pointed out three of the best stocks in personal computing. Here are two more I believe are worth watching. They're definitely facing some challenges, but they deserve a spot on any PC-minded investor's radar.

AMD continues to struggle
Chipmaker AMD (NASDAQ:AMD) is heavily exposed to the PC market. About half of its revenue comes from its Computing and Graphics segment, which is primarily composed of AMD's PC processors and graphics cards. Fortunately for AMD, neither is a particularly competitive market -- in each instance, AMD faces only one competitor -- but AMD is still far behind in both segments.

When it comes to discrete graphics cards, competitor NVIDIA accounts for nearly 80% of the market, while Intel holds a similar share of the market for PC processors. AMD's lower market share is primarily a byproduct of its product portfolio -- in most segments, AMD's offerings simply aren't as good. AMD has been able to supply cheaper products to the cost-conscious, but it lacks high-end offerings.

AMD's top desktop processors are outperformed by Intel's high-end Skylake processors. In the laptop segment, AMD's APUs are offered in many mid-level notebooks, but higher-end portables are almost exclusively the domain of Intel.

The situation in graphics is similar. AMD's low-end and mid-range cards match NVIDIA's offerings, but its flagship cards fall short. Its Radeon R9 Fury X is priced competitively with NVIDIA's GTX 980 Ti, but doesn't offer as much power.

But all of that could change, which is why AMD remains a stock worth watching. New processors, based on its Zen architecture, are expected to make their debut toward the end of 2016. Zen CPUs should offer significantly better performance -- around 40% more Instructions Per Clock (a measure of processing performance). AMD also intends to launch graphics cards based on its new Polaris architecture. Polaris-based GPUs should offer far better energy efficiency than AMD's prior cards, and could be ideal for thin and light laptops.

Photo: Hewlett-Packard

HP derives almost all of its revenue from PCs and printers
U.S. investors interested in traditional PC-makers have increasingly few choices. Many of the firms that make PCs are private, traded on Asian exchanges, or derive more of their revenue from mobile devices than desktops and laptops. HP (NYSE:HPQ) is a notable exception.

It's the second-largest PC vendor in the world, and shipped just over 14.2 million PCs last quarter, according to Gartner. That was a drop of about 8.1% on an annual basis, but its market share rose modestly, from 18.7% to 18.8%.

On HP's most recent earnings call, CEO Dion Weisler admitted that the PC market remains tough. In particular, demand from consumers has remained depressed. But HP is winning over enterprise customers. Last quarter, its share of the enterprise market rose to 23.7%, an all-time high for the company. Weisler doesn't expect the larger PC market to rebound in the immediate future, but is focused on taking share and improving profitability.

It's worth noting that HP also has a significant printer business. Printing generated nearly 40% of HP's revenue and around 75% of its earnings last quarter. But the market for printers appears intimately linked with the market for traditional PCs, particularly in an office environment.

With a price-to-earnings ratio in the low single-digits, it's clear investors aren't expecting much growth from HP. A rebound in the market for traditional PCs could help HP outperform those low expectations.