[Windflier]

Depending on what version of Windows XP, you can upgrade it to Windows 7.

I've got the home version of XP on both computers. I have the Win XP authentication code for one computer, but not the other.

Any idea of what it costs to do the upgrade? Perhaps I could at least upgrade one.

[American Constitutionalist]

I should have clarified what I meant, what I meant by what version of Windows XP, the latest, or later versions.
I was told by some computer tech guy that the last or latest version can only be upgraded to Windows 7.

[American Constitutionalist]

You would have to go to Microsoft website and download the compatibility software and see if that version of Windows XP is compatible with Windows 7.
You might still need at least 2 gigs of Ram for that.

[American Constitutionalist]

Before you spend any money...
You can do a nondestructive restore of your operating system that will not delete your data i.e photos, music, videos.... but, you would have to reinstall any applications that you have installed when you got the computer.
Or ? you can do a total destructive restore of your operating system, this option will reformat your hard drive and delete anything on your hard drive and reinstall your operating system as it was at the factory....
Do you still have to restore disks ? or is there a Recovery D: partition ? if not, then you will have to get the serial numbers off the side of your computer and call the manufacture of that computer for the restore disks for that computer model.
Have you checked inside ? lose wires ? lose memory ? does the power supply unit smell like it's burnt ? how about the metal heat sink on top of the CPU ? is it clogged up with dust ? like the other poster said, check the heat thermal paste and see if it's dried up and get new heat thermal paste and reset the heat sink on the CPU.

Have you run virus scan ? malware scan ? Disk defrag scan ? have you updated Windows XP ? the drivers ?
How about the Keyboard ? how old is it ? did coffee ? water get on it ? a new one you can get for about $ 15-30 ....
If Firefox caused it to freeze up, un-install Firefox to a older version.
What wattage if your power supply unit ? check the back of it, PSU ( power supply units ) are actually cheap, get one over $ 30.

[American Constitutionalist]

It could also be something simple as a bad driver or corrupt driver for the USB hooked up the the keyboard.
Another thing about the PSU ( power supply unit ) when they go bad ? the computer acts really fully and can actually shut down by it's self.
It won't hurt even if you get a new PSU with a few more watts than the old one... most of the time, the manufactures put lame PSU units in computer that just barely supplies power to the computer.
100 extra watts won't hurt, and your computer only uses that wattage when it needs it, lets say ? a 500 watt PSU ? it's not going to continually run at 500 watts max all the time.... now ? if you have a heavy use of multi-bluray drives, 2 GPUs a 6 core CPU, then yes, that 500 will be used most of the time.

[American Constitutionalist]

Sorry for all the typos,, tired and my eyes are going bad.