Large enterprises have spent mountains of cash tracking how their complex, multitier applications perform while traversing the network. But unless you're managing end-user data at the packet level, you're not getting the full picture of how customers and employees are affected by performance degradations--and when it comes right down to it, all the high-level metrics in the world don't matter if end users are lighting up the help desk complaining of sluggish performance while customers abandon their shopping carts.

Technologies exist to monitor every aspect of traffic, from keystroke to database, and many of the 30 or so software vendors we talked to for this article believe end-user performance monitoring will be the next big wave in enterprise application management spending.

We're not so sure.

First, few organizations are ready for this shift. We've spent a fortune over the decades on infrastructure management systems that do little to capture the user experience. Moreover, end-user-centric management is harder than conventional infrastructure management. Vendors will try to contradict this, pitching appliances that can be set up in a snap. Don't be fooled: The real work comes in correlating and aggregating mountains of logs, as well as capturing and incorporating app-specific data that requires client- and server-side agents. And if SOA, mashups, and Web 2.0 figure prominently in your network, be aware that management vendors have been slow to adopt standards that use these technologies to correlate complex data streams.

Meanwhile, IT organizations face pressure to limit staff growth, even as the complexity of the architecture increases. One IT manager told us that he sees determining the cause of application problems as more art than science. In his organization, the help desk is the first indicator of a problem. Only after enough calls come in from irate users does troubleshooting begin. By then, there isn't time to coolly assess the impact or weigh this issue versus other problems already in the queue. IT is in firefighting mode.

And what of the business impact? Are customers unable to order DVDs, move money from checking to savings, or process payroll?

Most user management and packet-capture technologies collect massive amounts of network data, all the better for troubleshooting. But because they typically don't have agents installed on user desktops or the app server, they provide only limited overall visibility into the cause of a slowdown.

Alternative approaches that use agents, however, also present problems. An agent may be the best way to capture the actual user experience, but that accuracy needs to be weighed against the higher cost and maintenance requirements of this approach. To help you decide which is the best route, here's a rundown of user-monitoring methods.