First prerequisite is to have WPA-capable equipment. If the modem/router/gateway thingie doesn't have WPA capabilities, but your cards do, then you could disable your modem/router/gateway's wireless capabilities entirely, and put a WPA-capable wireless router inboard of it, and have your systems connect wirelessly to that instead.
If you get to the point where you're going to do this, realize that it's not quite as simple as plugging the pieces together in order. You would probably need to log into your new router's configuration menu and change its default IP-address settings to a valid alternate scheme that's dissimilar from the other router, so that routing can occur.
Ok well I think i'll just stick with WEP for now .
I am now having problems with the computer (desktop) connected to the wireless network . It keeps on connecting and disconnecting but the signal strenght isn't low or anything, i tried 'repairing' the connection but it hasn't seemed to have done anything ,.
When encryting with WEP, should I use 64bits, 128bits or 256bits??