Two main desktops at home;
20" iMac Alum 2.0 Ghz - Use it for iTunes, email, browsing and serving up content to my Xbox 360, maintaining my web sites and editing home HD video.
Sony Vaio P4 2.4 Ghz, running Windows XP media center, use it to serve up recorded TV for the Xbox 360 and for some windows programs like Quicken
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Two main laptops (and a tablet);
MacBook Pro 2.2 Ghz purchased in January, use it for personal travel, email etc. blogging, and accessing work email through my browser.
Dell Latitude D830 Duo Core 2.0 Ghz - Used for the majority of work tasks and the majority of work travel, accessing the business VPN etc. (it runs Vista and even though it is new, it crashes and generally frustrates me, although I do like Office 2007)
Samsung Q1 UMPC - Use it only for note taking when i am in a business situation where using a keyboard would feel intrusive. Once in a while I put a movie on it and take it camping or something.
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We have other computers but those are the main ones used.