I have windows version 5.1. How do I upgrade?

There is no upgrade path from XP to Windows 7. You will have to back up your data and do a clean install, and re-install your programs.

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Windows 5.1, eh? So, I take it you must be using Windows XP! Upgrading to a more recent build should be fairly easy; all you have to do is purchase a more recent version of Windows (Windows Vista or Windows 7, I personally recommend the latter of the two) either in physical form at a local retailer, or in a downloadable form online straight from Microsoft's website. From there on, simply install the new operating system on your computer and move on from there! It should be a fairly straightforward experience.

Now before upgrading, you may want to take the condition of your current computer into consideration. Is your current hardware powerful enough to be running a more modern operating system? If it is several years old, it may not be capable of running some of the newer applications out there today at maximum efficiency.

Also, you may want just to back up the contents of your hard drive before updating! It's always good to have something to fall back on in case you want to return back to your current setup.