Network issue using Time Warner, Airport Extreme, MacBook Pro OSX, Windows7

I have the following on my home network:

- Time Warner cable-internet and phone service.
- Apple Airport Extreme Base Station hooked up to the cable modem
- MacbookPro running OS 10.6.3 connected wirelessly to airport extrm
- HP Laptop running Windows 7 connected wirelessly to airport extrm
- HP Officejet Pro 8500 connected to wirelessly to the airport extrm
- iPhone connected wirelessly to the airport extrm
- XBox connected via ethernet cable to airport extrm
- USB external hard drive connect via USB cable to airport extrm

My network worked fine with only my Macbook Pro, Airport Extreme, iPhone, XBox, and occasionally my buddy's Macbook Pro all on the network at the same time.
I recently added an HP Laptop running Windows 7 and a wireless HP Printer to the network at the same time.
Now if both the Windows 7 PC and the Macbook Pro are on the network at the same time, one of the machines will get booted from the internet. At one point, I got a message on my MacBook Pro that said another computer on the network is using the same IP address. I also have trouble communicating with the new HP printer if both the Windows 7 and the Macbook Pro machines are on the network at the same time.

How should I set up my airport extreme to allow all machines to function properly on my network. Right now, the network is set up to receive IP addresses automatically through the DHCP server. I read somewhere that maybe setting up the computers to manual static IP addresses and manually entering in the DNS server info into the airport extreme may fix my problem. I also read that configuring the network to all share a single IP address will fix the issue. How do I set this up. I would also like to keep my network invisible from being seen. Is this still possible?

Thanks for your help on this!!