Take off the password and see what happens. Security does slow things up, WPA more so than WPA2, but this problem has just come up so that's just a stab in the dark.

Your mini gives a stronger signal than the router, distance the same?

You have the Express right? Reconfigure it to temporarily be the router.

Our local MicroCenter has the D-Link 624 for $14.99, that would be a long drive for you though. grin I'm picking one up for a customer and one just to have around. I don't need n speed wireless, anything needing speed is wired, but the g is good for my laptop.