We know how this ends — with tech-company shareholders footing the bill. Cisco wrote off $900 million in bad debt in 2001. It will surely claim to have learned its lessons since then. But as others rush in to help customers acquire their wares, some will surely get burnt. As will investors, who may think they're buying shares in a tech company, only to discover they've put money into a bank.

One company which listened, to its detriment, to shareholders was Microsoft. When Bill Gates ran the software company, he liked to keep a year's worth of expenses on hand, in case things went awry. Microsoft is no longer quite so stingy with its cash; it dribbles some out in dividends, and gave shareholders a $32 billion payout a few years back. Good thing it didn't shell out $44 billion for Yahoo; that deal would have left it cash-poor and debt-ridden, at exactly the wrong time. Even so, Microsoft's balance sheet is no longer the most sterling in tech.

So who's got cash on hand? Here are the 10 richest tech companies, from a Yahoo Finance screening. (I left out companies, like IBM, whose cash was matched by equally outsized debts.)

1. China Mobile, $31.0 billion
   China's oil, steel, and finance giants are investing overseas. Why not its leading wireless company? Yes, China censors its citizens. That was a trendy thing to worry about in August 2008.
2. Cisco Systems, $26.2 billion
   Cisco's so proud of its cash pile, its investor-relations chief has blogged about it. If only investors had any confidence in Cisco's bizarre social-network acquisition strategy, which has nothing to do with its fine telecom-equipment assets. Memo to Cisco's M&A team: Just because it has the word "network" in it doesn't mean you have to buy it.
3. Microsoft, $21.2 billion
   The $44 billion Yahoo offer was half in cash, half in stock, which would have strained Microsoft's finances and required it to take on some debt. Good thing it fell through.
4. Apple, $20.7 billion
   In the '90s, Apple almost ran out of money. No danger of that happening soon. Ever-secretive Apple rarely makes big, splashy acquisitions; that could change if the right bargain comes along.
5. Google, $12.7 billion
   A slumping share price may mean more acquisitions done for cash.
6. Intel, $12.0 billion
   Intel's chip factories require billions of dollars in investment; count on Intel to spend its money there, rather than on cute Web companies.
7. Nokia, $10.8 billion
   Like Cisco, Nokia's eager to be more of a Web player. Blogging and lifecasting are particular areas of interest. The cell-phone maker could throw investors a curveball and buy, say, Six Apart, Automattic, or Tumblr.
8. Dell, $9.0 billion
   Dell could have more cash on its hands if it manages to sell its PC factories, a move it's considering as HP chips away at its business. On the shopping list: software and services.
9. Motorola, $7.2 billion
   It's hard to see Motorola being an active acquirer until it figures out what to do with its cell-phone business.
10. Taiwan Semiconductor, $7.0 billion
    AMD's only worth $2.6 billion, and TSMC already makes some chips for it. Why not just buy it?