1 big house - 1 IP address - more than 5 clients?

Question

Hi there.
I’d like to ask this fantastic discussion group for advice on the following:
I (more or less) voluntarily accepted the task to wirelessly connect our house to the internet using cable internet service. This is the situation:
Our 2.5 floor (sizable) house accomodates 10 rooms translating into up to 10 individual people/computers which want to connect to the internet wirelessly at the same time.
A Netgear wireless gateway (came with the cable contract) has been extended via ethernet using an Airport Extreme base station. As an additional extension, an Airport Express station was configured to connect wirelessly to the Airport Extreme as a remote base. The Airport Extreme base was set to share the single IP address that was given to us by our ISP using the 10.xyz... numbering system (which is different than what our ISP uses). The Netgear uses channel 1, the two Apple stations channel 11 and all devices were distributed in several rooms of the basement.
My questions would be:
1. Since the Airport Extreme base distributes addresses using DHCP and NAT, is there an upper limit on the number of computers that can have internet access at the same time (our ISP says that only up to 5 computers can be hooked up at the same time using the Netgear device)?
2. If it’s possible to have up to 10 computers connected this way, would the only thing restricting the perfomance for us all be the connection speed (in addition to the reception, of course), i.e. could we get away by increasing the connection speed to make things smoother (by upgrading our contract with the ISP; we're on 6 Megs right now)?
3. Is this a reasonable way to set things up or are there smarter alternatives?
I am aware of the fact that i could try out a lot more on my own than i already did, it’s just that the other people are not totally crazy about this kind of experimentation (we still have to work on some reception issues in addition) so, i am asking to avoid a revolt
Thanks bunches.
PB G4   Mac OS X (10.4.3)  
PB G4   Mac OS X (10.4.3)  
PB G4   Mac OS X (10.4.3)  
PB G4   Mac OS X (10.4.3)  

Answer 1

Your method is reasonable, though not optimum. However it may be the best for you needs, since you ended up not having to run any Ethernet cabling.
In my own home, we have both wired and wireless connections. I use multiple Access Points, connected back to the router to distribute the wireless signal though out the house, and to an out-building about 250 feet away. Each AP has the same SSID and security settings, but they are configured to use different channels, in our case 1, 6, and 11. Two of the Access points use omni antennas to distribute the signal within the house, and the third uses a directional semi parabolic reflector antenna to send the signal to the out building.
The advantage of using multiple Access Points via wired Ethernet is that you don't downgrade the wireless performance by having to repeat the signal using a wireless repeater.
As far as the Netgear cable modem. I would guess that your cable company has it configured to only have a limited number of DHCP assigned IP's available. Since you have the Cable Modem connected to the Airport Express, and the Airport Express is handling your DHCP IP assignment, you should not have an issue with the "5" user limit.
As far as upgrading your cable connection, only you can decide if a 6 MB connection is enough (I would think so). However, I would be more concerned about the upload speed then the download.
Tom N.