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I noticed in some of my client software, there are different options:

-WPA
-WPA-psk
-802.1x
-pre-shared key

I'm confused. I thought there was only one type of WPA. In a 3com WAP we have at work, we are using WPA-PSK. What would be the difference between this and regular "WPA" if I were to check the box? Also, isnt WPA-PSK just as weak as WEP-psk since it is essentially the same theory? These are my only questions.
Thanks