is my network secure?

From: Fred (Fred.Thomas_at_stamco.com)
Date: 11/27/05 

Date: Sun, 27 Nov 2005 04:52:37 -0000

My network is set up as below;

Could anyone advise as to whether there is anything else I could do to
enhance security?

Bexhill Road 217.204.190.13 - Easynet. ADSL Username is
sussexturnery@easydsl.net, Password tungau87 Tel 0800 053 4343

Churchfields 81.174.162.232 - Plusnet. ADSL Username is
stamco@plus.net password orange. Contact via www.plus.net
<http://www.plus.net/>

Hove 80.229.37.79 - Plusnet. ADSL Username is
stamcohove@plusdsl.net password orange. Contact via www.plus.net
<http://www.plus.net/>

External POP3 (email) server mail.demon.net username
stamco password rtrv4GL

FTP Addresses (Web-sites) ukupload.demon.net username stamco
password rtrv4GL (Main stamco.co.uk site)

                                                ftp.plus.net
<ftp://ftp.plus.net/> username stamco password orange
(stamcoshop.co.uk site)

Internal routers;

            Bexhill Road 192.168.1.248 Telnet/SSH;
Username kcceng password kcc123

            Bexhill Road ADSL 192.168.254.254 Internet Explorer;
Direct connection

            Churchfields 192.168.2.248 Telnet/SSH;
Username kcceng password kcc123

            Churchfields ADSL 192.168.2.247 Internet Explorer;
blank username password orange

Hove 192.168.3.248 Telnet/SSH; Username
kcceng password kcc123

            Hove ADSL 192.168.2.247 Internet Explorer;
blank username password orange

Servers;

            STAMCO_ONE administrator
orange

            STAMCO_TS1 administrator
orange

            Email/Intranet (192.168.1.1) admin
orange (connect either via telnet or http://192.168.1.1:10000
<http://192.168.1.1:10000/> ) - This also controls DHCP

            Phone Stats database (192.168.1.244) root
orange (connect via telnet or http://192.168.1.244:10000
<http://192.168.1.244:10000/> ) - Also has redundant DHCP server

            K8 (192.168.1.249) kccs
5t4mc0123 or root sta0098

            KPRINT kccs
kcc123