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  Ubuntu is a computer operating system (OS) offered under the open source methodology, which means that you can use, manipulate and share this operating system without paying a licensing fee. This OS is based on the Linux system. A wireless adapter allows you to connect to Internet using a wireless local area network (WLAN) connection, and you should ensure that your wireless adapter is compatible with your Ubuntu OS before you purchase it.
  
  

AirLink Wireless PCI

• The AirLink AWLH3028 Wireless Peripheral Component Interconnect (PCI) Adapter is compatible with the Institute of Electrical and Electronics Engineers (IEEE) 802.11g/b system, and it can transfer data up to 54 megabytes per second (Mbps). It supports Wireless Internet (Wi-Fi) Protected Access (WPA)-Phase-shift keying (PSK) data protection, which encrypts and password-protects your data when you send it over a Wi-Fi connection. This adapter fits into the PCI slot on your computer, and it comes with a one-year limited warranty. The AirLink AWLH3028 Wireless Adapter is an internal wireless adapter. This product costs approximately $13 in 2010.
  
  

Netgear MA521

• This wireless adapter can transfer data up to 11 Mbps, and it has an efficacy range of up to 300 feet. It is 802.11g compatible, and it comes with Wired Equivalent Protection (WEP), which encrypts your data for security purposes. The Netgear MA521 is designed for notebook computers, and it is compatible with computer with processors faster than 400 MegaHertz (MHz). This network adapter fits into the PCI cardbus slot on your computer. This product costs $59.96 in 2010.
  
  

KLG-520

• The KCorp KLG-520 wireless network adapter that fits into your PCI cardbus slot, and it is designed for laptop and notebook computers. This network adapter transmit data at speeds up to 108 Mbps, and it is compatible with 802.11b/g devices. It comes with a setup wizard, which guides you through the process of installing this device on your computer. Other features of this card include that has a WLAN light-emitting diode (LED) light to let you know whether or not you are connected to WLAN connection, and it comes with WEP and WPA protection. As of 2010, this product costs between $10 and $20.
  
  

Compaq W200

• The Compaq Wireless LAN Multiport W200 adapter is 802.11b compatible, and it comes with WEP protection. This device allows you to connect to Wi-Fi hotspots, which is an area that offers Wi-Fi over a WLAN connection. This device plugs into your desktop via a universal serial bus (USB) connection, and it can transfer data at speeds up to 11 Mbps. As of 2010, this product costs $50.