I'm sure it's like Windows 9x - it's the lowest-common-dumbass-denominator approach.
Windows will do its own primitive NATing of the internal network. The internal interface will be set to 192.168.0.1 and Windows will set up its own DHCP server to hand out addresses to internal machines. Once installed you can, IIRC, change the network address to 192.168.whatever, but there is no point, just let Windows do its ass-stupid thing and live with it.
You could change your DSL router to use 192.168.1.0 instead of 0.0 as network address. That's what I'd do in your situation.