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Last version for a Pentium III processor


I have a very old Thinkpad 600x that has a Pentium III (coppermine) processor. The current system requirements for the latest versions of Firefox reference a Pentium 4.

I'm currently running 3.5.13. None of the current add ons work with this version. What is the last version of Firefox that will work with a PIII? Operating system is XP, SP3. I want to install some form of Ad Block, and none are compatible with 3.5.13.

Additional System Details

Installed Plug-ins

  • Default Plug-in
  • Shockwave Flash 9.0 r16
  • Shockwave Flash 10.0 r22
  • Windows Presentation Foundation (WPF) plug-in for Mozilla browsers
  • Google Update
  • VLC media player Web Plugin 2.0.2
  • Java(TM) Platform SE binary
  • Adobe PDF Plug-In For Firefox and Netscape
  • The QuickTime Plugin allows you to view a wide variety of multimedia content in Web pages. For more information, visit the QuickTime Web site.
  • DRM Netscape Network Object
  • Npdsplay dll
  • DRM Store Netscape Plugin


  • User Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv: Gecko/20100914 Firefox/3.5.13

More Information

  • Top 10 Contributor
  • Moderator
2046 solutions 8901 answers

hello, have you tried it with the latest version from getfirefox.com (firefox 19) - the requirements state "recommended hardware" (so this might leave a little bit of leeway)?

  • Top 10 Contributor
  • Moderator
10756 solutions 96803 answers

Firefox 3.6.28 should also work:

Question owner

This is a 450 mhz processor. Computer was built in 2000 and still works like a charm. But so much today requires newer, faster hardware. The HD on this thing is only 25G, but it originally came with a 10G HD.

I should think that there might be vast numbers of people out there with functional, but outdated, hardware who still need to access the web and be safe and secure. It kind of upsets me that Mozilla would not continue to support the browsers that work for people in that situation.