cannot connect to router logon screen

This involved a home wireless G network that includes 3 PCs, 2 running
XP and one running Windows 7. There are 2 routers connected to each
other by cable to extend the range. The problem router is a SMCWBR14-G.
The wlan was set up years ago and runs fine and connects fine to the
internet via Cox cable.

My problem is that I cannot access the SMC router's logon screen. When I
try to reach 192.168.2.1 with either IE8 or Firefox 3.1.2 on any of my
PCs, I get "waiting for response" until finally the connection resets.
This happens whether I use a direct cable connection or try wireless and
both with the PCs using XP or Windows 7.

Yet the router works and connects to the internet just fine on all these
PCs!

I finally found an old laptop I had not used for years, a Dell Inspiron
8100 running Windows XP and it connects and opens the logon screen even
wirelessly just fine. But I need to be able to access the logon screen
from another more recent PC.

I've played around with various settings, disabled my firewalls, all to
no effect. I suspect the problem may be that my current PCs use ips of
192.168.1.xx (because of my main router) while the Dell is a 192.168.2.xx

I really do not want to mess around and change with the ips on my
current PCs and possibly mess up my current wlan and internet access. Is
there a way around this access problem?

Thank you.