802.11i - new generation of wireless security.

802.11i is an appendix to 802.11 standard that specifies a new generation of a wireless security. IEEE 802.11 is standard on which wireless LAN networks are based. This original standard has used WEP for security. WEP is relatively easy to crack.
Here you could find out how WEP is cracked in less then a minute.

IEEE 802.11 group was aware of this security problem and on June 2004 they approved an amendment on 802.11 – 11i. They add much stronger encryption, authentication, and key management tactics that guarantee data and system security.

More about WPA and WPA2 you could find here.

If you want to use WPA2, you need firmware upgrade (on access point or wireless router) and driver update (on client adapter). So, as you can see, both client and wireless router (or access point) need to support WPA2. This updates you can find on vendors web sites. Maybe you will need to upgrade OS too.