Dell makes cheap functional machines. Apple makes expensive consumerist lifestyle fashion. In the current economic environment Apple is a better short than Dell.
Toshiba and Sony also make machines with design value add. Dell, not much. Gateway/Acer, not at all. HP, maybe more than Dell, but not especially.
Ten years ago, almost all the market was in generic desktop boxes, and notebooks were a minor category. Dell's manufacturing and supply chain expertise allowed them to differentiate their systems through cost savings and through rapid production of customized systems. They could carry a few more components and sell people better boxes just by swapping in the right components.
Now, the problem is that generic boxes are purely a low-margin commodity, and all the margin is in systems that are actually engineered. Macs. Thinkpads. Elaborate gaming systems. Stuff where you don't just switch out a part or two and call it a different box. And that's not Dell's game.
With service contracts outsourced to Bangalore (or other off-shore or off-site locations), users of Dell equipment at these corporations are becoming more and more flustered. They can't get their machines fixed in a timely manner, and are locked in to long-term contracts negotiated by executive board members who don't use the machines on a daily basis.
When you say that Dell makes "cheap functional machines", I'd argue that they're simply in the business of making cheap machines these days. Functional machines, I'd argue, would be able to withstand the rigors of normal (10hr/day) usage.
One of the mains reason Apple succeeds today is because their equipment works. Lenovo is also succeeding, despite its ties with Microsoft. (Also, it doesn't hurt that Apple has stores all over the country where you can get live, in-person help with your machine.)