Announced in 2007 the OQO model 02 packs quite a punch for a small pc. Read more about it in the following review.

First some specs. The OQO has a 1.5GHz Via C7-m ULV processor and 1GB SDRAM memory. The HDD is 60GB and the screen is a 5" LCD with a resolution of 800x480. The OQO has both wireless and bluetooth. The weight is 1.0 lb and the size is 5.6” x 3.3” x 1.0”.
The battery is a standard 4500mAh li-ion polymer battery and it ships with a AC power supply and VGA/ethernet adapter. The OS is Windows Vista Ultimate but there are also models with Windows XP Tablet PC Edition 2005.

The unit is made out of magnesium aloy and black plastic. The slider works on metal side rails making the screen run smoothly.
 
You can connect an external monitor with the VGA port or you can use either HDMI or DVI. A great feature is the automatic brightness adjustment using a sensor.

Sliding the display reveals the thumb keyboard which works amazingly well. On the left side of the keyboard mouse keys make control even easier. You obviously won't get the same responsiveness or writing speed of a normal keyboard. However, with about 50% touch-typing speed of a normal sized keyboard the performance is one of the best in it's kind.

The OQO comes with a fully featured OS, Windows Vista, so you can use it like any standard laptop or desktop. Video playback shouldn't be a problem nor should multi tasking. The OQO isn't as powerful as a standard lap- or desktop but for everyday use it works great.
Don't worry about running Vista on it. It should do just fine. Especially in booting, restarting and starting programs you could very well beat Windows XP in speed!

To wrap this small review up, here are some pros and some cons.
The first pro is it's weight. It doesn't weigh anything really so you can hold it for a long time without getting tired. Another pro is the power of the machine. Yes, other machines can be more powerful but the OQO makes good use of what it packs.
The last pro is the quality of the keyboard. After getting used to it initially, the keyboard works really well.
Some cons are batterylife and price. The battery will typically work for about 2 hours which isn't long. This can be solved by buying a double capacity battery. The price is also quite high starting at $1299. Of course most UMPC's are costly and with a nice design, good performance and easy navigation the OQO model 02 may very well be worth your money.