Assign IP Address

Hello,
We have a ethernet cable (running from local sql server pc router) being connected to 8-port LAN switch(s1).From this switch, 2 ethernet cables are taken as output and connected to 2 different LAN switches(s2 & s3). To each of the three switches(s1,s2&s3) a modem is connected(s1-m1,s2-m2,s3-m3) for internet access.
Now s1 has 3 three pcs connected, s2 has 4 pcs connected and s3 has 7 pcs connected for local server and internet access. I need to assign IP adress via modem settings so that pcs connected to s1-m1 have ips gateways diffenrent from that of s2-m2 and inturn s3-m3.please help.
For eg:

s1-m1-192.168.24.100-Modem IP (Gateway)-Ip range for pcs-192.168.24.101 to 125
s2-m2-192.168.24.200-Modem IP (Gateway)-Ip range for pcs-192.168.24.201 to 224
s3-m3-192.168.24.225-Modem IP (Gateway)-Ip range for pcs-192.168.24.226 to 234

Is this correct?Kindly guide me in this case.OS used in PCs-Vista,XP,Win2000
Thank U.