Final answer:
The dominance of Microsoft and Intel in their respective markets exemplifies the bargaining power of suppliers in the Porter's five forces model, as they have significant leverage over PC manufacturers.
Step-by-step explanation:
In relation to Porter's five forces model, the fact that about 90% of the world's nearly one billion PCs run on Microsoft's operating systems and 80% use Intel's microprocessors represents the bargaining power of suppliers. Both Microsoft and Intel are primary suppliers in the PC industry with significant market share. As such, they have considerable leverage over manufacturers who rely on their products.
The antitrust concerns related to Microsoft highlight the impact of having such a strong bargaining position. Microsoft's ability to influence the market and set terms with manufacturers illustrates the power they hold as a supplier, especially when this power is used to limit competition by tying products together or engaging in exclusive agreements.
The situation described in the question represents the aspect of the Porter's five forces model known as threat of substitute products. This is because the high market share of Microsoft's operating systems and Intel's microprocessors make it difficult for other companies to compete effectively in the PC market. The dominance of these two companies creates a barrier for new entrants and limits the availability of substitute products.