airport express setup noob question

Here is my set up:
1 Mac powerpc
1 dell desktop running vista
1 macbook pro
Airport express and Netgear 5 port fast ethernet switch

I am using the airport express for the wireless for my mbp and iphone. However, since I dont have wireless cards on my my mac and PC, I need to use a LAN line. so right now I have a connection from the modem --> netgear hub --> airport express which give me wireless. But if I use ethernet cables to connect from the netgear hub to both of the powerpc and dell, then they don't get connections. I believe it has to be with the settings and Ip adresses. I'm not sure how to set that up. Currently my airport utility shows:

Wireless mode: create a wireless network
wpa/wpa2 personal
using DHCP
IP address: 24.30.x.x
Sharing: share a public Ip address

any help is appreciated. Hope I wasnt too confusing.

 

thanks for your help. Strange thing is that I had the same set up working before. But when I was messing with it recently, it did appear as though it limits to either wireless or LAN (my wireless got cut off then the LAN started to work). I had a TEW 623pi card for my Dell and it never worked with Vista, always freezed up my comp. So I finally decided to format my comp and downgrade it to XP, the card is working fine now so I have wireless on my dell pc (currently playing spore on it,

thank you again for the help.