Use guest network on wireless router WITHOUT enabling DHCP (using SBS 2008)?

A small business client was using an older Netgear wireless router that had a guest network feature (don't recall the model). It worked fine even though DHCP was turned off on the router (SBS 2008 Server was handling DHCP).

The Netgear died and I replaced it with the Cisco e4200. Unfortunately, it looks as though the e4200 guest network, as far as I can find out, will not work without the e4200 handing DHCP. The guest client seems to connect but does not get an IP address and cannot access the internet.

I guess I have 3 questions:

1. Has anyone been able to successfully get the guest network on the e4200 to work without DHCP enabled?

2. Has anyone found a decent wireless router for a small business without a big budget that has a working guest network without requiring DHCP to be handled by the router itself?

3. Does anyone have a suggestion for a good "workaround" that does not include having another separate, dedicated internet connection?

Regarding number 3, I've seen some postings about "creative" ways to use a wireless access point, different subnets, etc.

My goal is to be able to offer wireless connections for guests to get on the internet without them having access to my client's physical network. Ideally, I'd want the internal network to be completely hidden from view, but  I guess if they could "see", but not have access to internal network, that might be acceptable.