Problems sharing internet connection over encrypted wireless

[osohardy]

Forgive me if this is answered elsewhere---I have found some info but had a few questions still:

I have my Imac set up as a basestation and want my mini to access over wireless. The imac is connected by ethernet to cable modem and airport turned on. Initally I went to sharing-->internet sharing (ethernet to airport) and under airport options there created a network name and encrypted by WEP pass. However, the mini would time out trying to connect. Without WEP it connects.

But really I dont want to use WEP but WPA. I noticed that if I create an airport network in the network prefs instead of via the internet sharing dialog there are many more options there including WPA....so my question is then do I create the WPA network there....then when I turn on internet sharing what do I do under airport options?

And why wouldn't it like the WEP password in the first place?

Thanks for any help!