Q: I have a Mac OS X 10.4.11.  I bought it new but never updated.  What would I have to buy to bring my computer up to date.

This depends on what model you actually have. There are many different iMac models. Specifically, which one do you have? The hierarchy is:

Leopard - the last system to work on non-Intel hardware.

Snow Leopard - Requires Intel-based hardware.

Lion - Requires a full 64-bit qualified model.

Mountain Lion - Requires a full 64-bit qualified model.

Mavericks - Requires a full 64-bit qualified model.

Upgrading to Snow Leopard

You can purchase Snow Leopard through the Apple Store: Mac OS X 10.6 Snow Leopard - Apple Store (U.S.). The price is $19.99 plus tax. You will be sent physical media by mail after placing your order.

After you install Snow Leopard you will have to download and install the Mac OS X 10.6.8 Update Combo v1.1 to update Snow Leopard to 10.6.8 and give you access to the App Store. Access to the App Store enables you to download Mavericks if your computer meets the requirements.

     Snow Leopard General Requirements

       1. Mac computer with an Intel processor

       2. 1GB of memory

       3. 5GB of available disk space

       4. DVD drive for installation

       5. Some features require a compatible Internet service provider;

           fees may apply.

       6. Some features require Apple’s iCloud services; fees and

           terms apply.

Upgrading to Lion

If your computer does not meet the requirements to install Mavericks, it may still meet the requirements to install Lion.

You can purchase Lion at the Online Apple Store. The cost is $19.99 (as it was before) plus tax.  It's a download. You will get an email containing a redemption code that you then use at the Mac App Store to download Lion. Save a copy of that installer to your Downloads folder because the installer deletes itself at the end of the installation.

     Lion System Requirements

       1. Mac computer with an Intel Core 2 Duo, Core i3, Core i5, Core i7,

           or Xeon processor

       2. 2GB of memory

       3. OS X v10.6.6 or later (v10.6.8 recommended)

       4. 7GB of available space

       5. Some features require an Apple ID; terms apply.

Upgrading to Mavericks

You can upgrade to Mavericks from Lion or directly from Snow Leopard. Mavericks can be downloaded from the Mac App Store for FREE.

Upgrading to Mavericks

To upgrade to Mavericks you must have Snow Leopard 10.6.8 or Lion installed. Download Mavericks from the App Store. Sign in using your Apple ID. Mavericks is free. The file is quite large, over 5 GBs, so allow some time to download. It would be preferable to use Ethernet because it is nearly four times faster than wireless.

    OS X Mavericks- System Requirements

      Macs that can be upgraded to OS X Mavericks

         1. iMac (Mid 2007 or newer) - Model Identifier 7,1 or later

         2. MacBook (Late 2008 Aluminum, or Early 2009 or newer) - Model Identifier 5,1 or later

         3. MacBook Pro (Mid/Late 2007 or newer) - Model Identifier 3,1 or later

         4. MacBook Air (Late 2008 or newer) - Model Identifier 2,1 or later

         5. Mac mini (Early 2009 or newer) - Model Identifier 3,1 or later

         6. Mac Pro (Early 2008 or newer) - Model Identifier 3,1 or later

         7. Xserve (Early 2009) - Model Identifier 3,1 or later

To find the model identifier open System Profiler in the Utilities folder. It's displayed in the panel on the right.

     Are my applications compatible?

         See App Compatibility Table - RoaringApps.

My mac is the first (I think) of the intel processer macs. The first of the iMacs came out in 2006. If you go to the Utilities folder, look for System Profiler or Apple System Profiler. Run the program. In the opening window you will see a list on the left and a panel window on the right. In that panel you should find a listing labeled like Machine or Model ID followed by "iMac" and two integers separated by a comma, e.g., iMac 1,1. If the identier is iMac 4,1 or iMac 4,2 then it is a Core Duo model. The highest version of OS X it can run is Snow Leopard - 10.6.x. So in your instance this would mean:

Upgrading to Snow Leopard

You can purchase Snow Leopard through the Apple Store: Mac OS X 10.6 Snow Leopard - Apple Store (U.S.). The price is $19.99 plus tax. You will be sent physical media by mail after placing your order.

After you install Snow Leopard you will have to download and install the Mac OS X 10.6.8 Update Combo v1.1 to update Snow Leopard to 10.6.8 and give you access to the App Store. Access to the App Store enables you to download Mavericks if your computer meets the requirements.

     Snow Leopard General Requirements

       1. Mac computer with an Intel processor

       2. 1GB of memory

       3. 5GB of available disk space

       4. DVD drive for installation

       5. Some features require a compatible Internet service provider;

           fees may apply.

       6. Some features require Apple’s iCloud services; fees and

           terms apply.

As I think more about what you've just said I'm wondering if you really want to upgrade or just start fresh. You could start fresh with the Tiger you have installed now provided you still have the original discs that came with the computer. If you don't have them, then Snow Leopard is probably the easiest way to go. But you might think about simply erasing the drive and starting from scratch as when the computer was new.

Well, there's little you do about that problem. It will always be too old for some things. The Firefox issue is easily solved - don't use it. There's nothing wrong with using Safari.

You do not need Leopard to upgrade to Snow Leopard. You just need to erase the drive and do a fresh install of Snow Leopard. Be sure you backup your Tiger system first.

The price of Snow Leopard was originally $129.00. It was lowered with the release of Lion because Snow Leopard was required to install Lion and later.

You can upgrade directly over Tiger, but I don't recommend it, hence, why I said you should erase the drive before installing Snow Leopard. I think this assures the least potential for problems.