Mini PCI is a standard for a computer bus for attaching peripheral devices to a computer motherboard and is an adaptation of the Peripheral Component Interconnect (PCI) bus. It was designed for laptops and other small-footprint computer systems.

Here is the card form, Type I, Type II, Type III, In laptop, we only use Type III

IIIA  124-Pin Card Edge  2.4 × 59.6 × 50.95 mm  (I called it “full size”)
IIIB  124-Pin Card Edge  2.4 × 59.6 × 44.6 mm  (I called it “standard size”/halfsize)

And there is a new model. I called it “compact size”. 2.4 × 59.6 × 24.6 mm

One single picture is better than 1,000 words, so, here it is:
<img src="http://www.heartyit.com/ebay/3minipci.gif">



In my opinion, the compact size mini pci is the best. Most of this type of cards has power-saving design, which may reduce system power consumption up to 98%. However, due to its compact size, the antenna cables of a few of laptop models are too short to reach the cardboard, so you need double check to make sure if your antenna cables are long enough for this card. According to my experience, in overall, 95% laptop's antenna cables should be ok. For specific models, such as DELL INSPIRON 5000/5100/5150, 80% antenna cables have no problem. if your antenna cables are short, and you also want to enjoy this compact mini pci wireless card, you need to buy a pair of antenna as the substitution of your current antenna cables.

The other option is that, you may buy a standard(half) size min pci card. Full size card only fit in some IBM's old models.

BTW: Mini PCI and PCI are cousins. You can use regular PCI cards with your Mini PCI-equipped hardware and vice-versa, using Mini PCI-to-PCI and PCI-to-Mini PCI converters. I sold some RICHO's chipset PCI-to-Mini PCI converters before, the feedback is perfect.