how to get free virus protection

[wynd7946]

this computer is a secondary computer  sharing a modem of another computer which is protected with avg free.i tried to load avg on this system but it said i need an upgrade or somethin to get protection. also am i right when they say only one computer per household?i also tried to load a norton trial  one and it said basically the same thing.is there an older version of these versions to cover an xp home edition[this is an ex office computer and my dad also refers to it as an windows xp proffessional]can anybody help me?nicole

[evilfantasy]

It sounds like it isn't a valid copy of Windows.

1. Download this diagnostics tool MGADiag.exe and save this to your Desktop.
2. Double-click on MGADiag.exe and click Continue
3. When the program has finished, click on Copy
4. Post the results in your next reply.