Not sure I agree - corporates can tighten their belts as much as consumers.
A lot of corporates might choose to delay upgrading products coming out of support and/or cancel their support agreements. These are lucrative part of Microsoft's revenue.
Apple is a luxury brand and Microsoft isn't, so I think the current economic troubles will hit them harder.
Apple (well, Jobs) doesn't focus on marketing to corporations as a strategy to be more appealing to consumers, but I'm certain if they had to they could. Do Sun have any desktop Unix customers left? They're Apple's obvious first target.
Apple uses style and design as key selling points and differentiators. Hence, the upscale nature of the brand. Apple will never sell anything that resembles an eMachine.