Compatibility

• Whereas a PCI card or built-in laptop wireless card is not usable in most other computers (or in none in the case of an integrated laptop WiFi card), WiFi USB cards are compatible with most every computer because most computers have USB.
  
  

802.11a/g vs. 802.11b

• Although 802.11a and 802.11g require USB 2.0 to work correctly, 802.11b meets the speed of USB 1.1, which nearly every computer today has capability for. This means that an 802.11b card is nearly universally compatible.
  
  

Portability

• WiFi USB cards are also very portable, with most being about the same size as a flash drive.
  
  

Downside of Portability

• A potential problem is that this small size makes a WiFi USB card easy to misplace if it is used on multiple computers in multiple locations.
  
  

Processor Usage

• WiFi USB cards tend to use more processor resources than a standard PCI slot card.