One easy way to get an idea of what your local network's DHCP scope is to look at a local device like one of your Windows 7 devices and run "ipconfig" and see what IP is assigned (as well as the subnet mask and default gateway.) Like I said generally these home routers use 192.168.1.2 - 192.168.1.254 (router takes 192.168.1.1 and 192.168.1.255 is a special broadcast IP: http://en.wikipedia.org/wiki/Broadcast_address) But some routers use completely different IP ranges, so I don't want to assume what yours will be.
What model is your router?
Either way, login to your router via a web browser, and see if you can find DHCP settings anywhere. What you're looking for is something like "Starting IP" for the DHCP settings. For example, on my linksys router, I change this setting to 192.168.1.50, so DHCP leases would start at .50 and higher. This leaves me 192.168.1.2 - 192.168.1.49 to assign static IPs to devices.
Once you figure this out, you can just pick a static IP within that range and assign it to your ESXi host, also using the subnet mask and gateway info you got from your Windows 7 device.
