MobileTechReview has a fantastic review of the OQO Model 01 computer. The OQO is a full blown Windows PC in a case the size of a PDA. It runs Windows XP Home Edition and has several ports for expansion and docking. Here's a clip...
"Make no mistake, the OQO model 01 is one of the most impressive technological feats of the decade. OQO spent five years developing this handheld computer, and likely it took every day to fit a PC into a device the size of a large PDA. The model 01, currently the only OQO model, runs Windows XP Home Edition rather than a PDA operating system, yet it will fit easily in a purse, brief case or roomy pocket. At 4.9 x 3.4 x .9 inches, the device isn't much larger than large Pocket PC and Palm models such as the Palm LifeDrive and HP iPAQ hx4700, though it is heavier at 14 ounces. For those who must have full blown Windows on the go in a tiny package, the nearly $2,000 OQO might prove indispensable. Since Windows XP wasn't designed for use in such a small format, usability does suffer, and we'll talk more about that later."
"Make no mistake, the OQO model 01 is one of the most impressive technological feats of the decade. OQO spent five years developing this handheld computer, and likely it took every day to fit a PC into a device the size of a large PDA. The model 01, currently the only OQO model, runs Windows XP Home Edition rather than a PDA operating system, yet it will fit easily in a purse, brief case or roomy pocket. At 4.9 x 3.4 x .9 inches, the device isn't much larger than large Pocket PC and Palm models such as the Palm LifeDrive and HP iPAQ hx4700, though it is heavier at 14 ounces. For those who must have full blown Windows on the go in a tiny package, the nearly $2,000 OQO might prove indispensable. Since Windows XP wasn't designed for use in such a small format, usability does suffer, and we'll talk more about that later."