A method and system for installing an application or a set of applications on a client device, such as a portable (or palmtop) computer system. The application(s) to be installed are identified. The host device has stored therein an operating system comprising a plurality of software routines. A subset of the operating system is generated. In one embodiment, the subset comprises those software routines needed to support the applications installed on the client device. In another embodiment, the subset comprises those software routines that, in combination with software routines used by the operating system on the client device, supports the applications installed on the client device. The application(s) and the subset are installed on the client computer system. Thus, the operating system of the client computer system contains only those software routines needed to support the installed applications, thereby efficiently using memory resources in the client computer system.