Microsoft

Microsoft's ambitions are anything but small. The world's #1 software company provides a variety of products and services, including its ubiquitous Windows operating systems and Office software suite. Microsoft has expanded into markets such as video game consoles, customer relationship management applications, server and storage software, and digital music players. The company has also used selective acquisitions to bulk up its presence in markets such as online advertising, mobile devices, and enterprise software. In 2008 Microsoft made repeated efforts to acquire Yahoo! but was ultimately rebuffed by that company's board of directors.

Cisco

Cisco Systems routes packets and routs competitors with equal efficiency. Dominating the market for IP-based networking equipment, the company provides routers and switches used to direct data, voice, and video traffic. Other products include remote access servers, IP telephony equipment, optical networking components, Internet conferencing systems, set-top boxes, and network service and security systems. It sells its products primarily to large enterprises and telecommunications service providers, but it also markets products designed for small businesses and consumers through its Linksys division.

Symantec

Symantec has never had a problem with insecurity. The company provides security, storage, and systems management software for consumers and businesses. Its applications handle such functions as virus protection, PC maintenance, data backup and recovery, intrusion detection, data loss prevention, spam control, content filtering, and remote server management. Symantec sells its products through a direct sales force, as well as through distributors, resellers, original equipment manufacturers, and systems integrators. The company also provides consulting, managed services, and training. Customers outside of the Americas account for about half of sales.

SonicWALL

SonicWALL puts up more than sound barriers -- the company provides network security devices and software. Its systems protect communications between headquarters and branch offices, secure broadband Internet access, and filter Web content (blocking a minor's access to adult Web sites, for example). Other products include data backup appliances and related software. It also offers services such as content filtering and intrusion prevention on a subscription basis.

Dell

Dell wants its name to ring from the desktop to the data center. One of the world's top suppliers of personal computers, the company offers a broad range of technology products for the consumer, education, enterprise, and government sectors. In addition to a full line of desktop and notebook PCs, Dell offers network servers, data storage systems, printers, Ethernet switches, and peripherals such as displays and projectors. It also markets third-party software and hardware. Dell's growing services unit provides infrastructure consulting, systems integration, asset recovery, financing, support, and training.

VMware

VMware develops software that creates and manages virtual machines -- computer functions spread across multiple systems that act as one. Companies use VMware's software to more efficiently integrate and manage server, storage, and networking functions, thereby lowering the operating costs of their computing resources. VMware also provides consulting, support, and training services. The company has marketing relationships with computer hardware vendors including Dell, Hewlett-Packard, and IBM. Founded in 1998, VMware was acquired by EMC for about $625 million in cash in 2004. Looking to unlock some of the value in its subsidiary, EMC sold about 10% of VMware via an IPO in 2007.