The first machine, the Vaio C1, is based on Transmeta's TM5800 processor, which runs at 867MHz, has 128Mbytes of double data rate (DDR) memory.
The machine doubles as a digital video recorder, using an external TV tuner unit and the bundled GigaPocket software to record TV programs to its 40Gbyte hard disc drive.
Sony has been bundling GigaPocket in Vaio desktop machines for some time, but this is the first notebook computer to include the software. The software has never been included on a notebook before because of the processing demands it puts on the machine. However, recent improvements in mobile processor technology, coupled with a hardware MPEG2 encoder chip which relieves the processor of much of the heavy work, have enabled Sony to do this on the C1.
The second new machine, the Vaio-U, is the smallest Windows XP notebook to date, the company said, and noticeably smaller than Toshiba's Libretto mini notebook computer. Like the Toshiba, Sony has chosen a Transmeta Crusoe processor, but gone for the faster TM5800 model.
Because it is so small, the machine is easy to hold with one hand on each side of the main body. Sony has included a number of design features to accommodate operation with two thumbs. Under the right thumb is a pointer, used to control the cursor, while under the left thumb are two buttons that mimic left and right clicking on a mouse. There is also a zoom-in button on the right hand side of the screen.
Inspiration has also come from the world of mobile phones, where one-thumbed operation for typing and sending e-mail is so common it is becoming second nature for many.
The ThumbPhrase system makes use of a shadow keyboard arranged like that of a mobile telephone, with one button representing several characters or letters, which is used by the left thumb while the right thumb controls functions such as capitalisation or switching between the different Japanese kana and kanji characters.
Both machines were previewed in early March, at the same time as Sony announced a new version of its Clie PDA, and are scheduled to go on sale in Japan on 27 April. Overseas launch dates have not yet been decided, Sony said.
In Japan, the Vaio C1 will cost ¥230,000 (£1,222) and the Vaio U ¥150,000 (£797).