Suggest upgrading to SP3 or later for invalid certificate errors.

chrome/app/chromium_strings.grd

 <?xml version="1.0" encoding="UTF-8"?>
 <!-- This file contains definitions of strings that are distribution specific.
 These strings will not be translated and only english versions will
 be available for now. -->
 
 <grit base_dir="." latest_public_release="0" current_release="1"
       source_lang_id="en" enc_check="möl">
   <outputs>
     <output filename="grit/chromium_strings.h" type="rc_header">
       <emit emit_type='prepend'></emit>
@@ skipping 1250 matching lines @@
       <if expr="is_android or is_ios">
         <message name="IDS_SSL_CLOCK_ERROR" desc="Paragraph explaining that the SSL interstitial is probably caused by an incorrect clock.">
           Chromium can't establish a private connection to &lt;strong&gt;<ph name="DOMAIN">$1<ex>paypal.com</ex></ph>&lt;/strong&gt;. This is probably because your device's date is set incorrectly (<ph name="DATE">$2<ex>Jan 1, 1970</ex></ph>). You should refresh this page after <ph name="BEGIN_LINK">&lt;a href="#" id="clock-link"&gt;</ph>you update your device's date and time<ph name="END_LINK">&lt;/a&gt;</ph>.
         </message>
       </if>
       <if expr="not is_android and not is_ios">
         <message name="IDS_SSL_CLOCK_ERROR" desc="Paragraph explaining that the SSL interstitial is probably caused by an incorrect clock.">
           Chromium can't establish a private connection to &lt;strong&gt;<ph name="DOMAIN">$1<ex>paypal.com</ex></ph>&lt;/strong&gt;. This is probably because your computer's date is set incorrectly (<ph name="DATE">$2<ex>Jan 1, 1970</ex></ph>). You should refresh this page after <ph name="BEGIN_LINK">&lt;a href="#" id="clock-link"&gt;</ph>you update your computer's date and time<ph name="END_LINK">&lt;/a&gt;</ph>.
         </message>
       </if>
+      <message name="IDS_SSL_NONOVERRIDABLE_MORE_INVALID_SP3" desc="Body text for the explanation shown if the user clicks on the details windows, the certificate is invalid and the user has an old version of Windows(before WINDOWS XP SP3) running.">

[felt, 2014/07/23 00:25:53]

nit: missing space "Windows(before"

[radhikabhar, 2014/07/23 00:39:38]

Done.

+      Your computer is running an old version of Microsoft Windows that cannot process this website's security certificate. Because of this problem, Chromium can't tell whether the certificate came from <ph name="SITE">$1<ex>google.com</ex></ph> or from someone on your network pretending to be <ph name="SITE">$1<ex>google.com</ex></ph>. Please update your computer to a more recent version of Windows.
+      </message>
 
       <!-- OOBE -->
       <if expr="chromeos">
         <message name="IDS_INSTALLING_UPDATE" desc="Label shown on the updates installation screen during OOBE">
           Please wait while Chromium installs the latest system updates.
         </message>
         <message name="IDS_CHECKING_FOR_UPDATE_MSG" desc="Chrome OS OOBE: message shown during checking for update stage.">
           Chromium updates automatically so you always have the freshest version.
         </message>
         <message name="IDS_UPDATE_MSG" desc="Chrome OS OOBE: message shown during update stage.">
           Chromium updates automatically so you always have the freshest version. When this download completes, Chromium will restart and you'll be on your way.
         </message>
         <message name="IDS_EULA_SCREEN_ACCESSIBLE_TITLE" desc="Title to be spoken on opening the OOBE EULA screen">
           Chromium OS terms
         </message>
       </if>
 
     </messages>
   </release>
 </grit>