Can I configure Netgear WGR614 to do this..??

I have a Netgear WGR614 (v5 I think). I am trying to figure out how (if) I can set it up where certain wireless connections (PCs in the store) can access each other as well as some other PCs connected to it by CAT cable, BUT also allow other wireless connections (visitors to the store) to only have access to the internet (and I'd prefer that the visitors not have to enter any keys or anything)?

Is this possible or do I have to do something with 2 wireless routers (one for the store PCs and one for the visitors)?

Thanks for any help!

The first thing that comes to mind is to have the file sharing network require passwords.

For the best security, having two routers on two different channels and networks (SSIDs, yours being secure) is probably worth the investment.

So if I have two wireless routers, how will I connect both of them to the one Ethernet port on our internet connection?

Usually, the more public router would connect to the internet modem, and would also handle DHCP. It would have no encryption.

The private router would be wired to the public router through LAN ports, have a different IP number (set manually, eg public=192.168.0.1, private=192.168.0.2), have DHCP turned off, and be set to broadcast on a different wifi channel. It would use encryption -- probably WEP if there are non-windows devices that need to connect wirelessly, and if you can set it to only allow the MAC addresses or IPs of your office devices, do so.

Your office devices would have fixed IP numbers (outside the range assigned by DHCP).

Use firewalls to protect the wired devices, and use passwords for file sharing.