IBM/Lenovo, HP/Compaq and Dell all have well deserved good reputations for the quality of their corporate grade hardware, service and support. Their consumer grade stuff is, in my experience, pretty dodgy. Proprietary parts, lower grade components and poor service and warranty support has led to pages and pages of griping about their respective consumer level offerings.
Where I work, we're standardized on IBM/Lenovo for everything...servers, workstations, notebooks, and monitors. Their service and support is exemplary. At home, I use custom built hardware, parts of my choosing and built by me.
Apple's take-it or leave-it hardware choices notwithstanding, I believe that if not for Apples innovation in design (iMac, Mac Mini), we wouldn't be seeing nearly the degree of customization from companies like Dell.