I think I am going to have a problem soon. I have been given a pc (very generous person) and when I switched it on it came up with a message that windows will not work in 15 days. I had no software or numbers come with the computer so do I just assume that after 15 days it will be useless! I am not very technically minded so please dont baffle me!!!!!
If the windows xp software wasn't validated, then it will stop working. After 15 days it will only allow you to bootup and use the internet for 1 hour per day (so you can purchase a serial number for it.) You can always download a linux livecd and still use your computer. It'll bootup and let you surf the internet etc without installing to hard drive. Theres different sizes and types ubuntu the most well known (similar to vista) http://www.ubuntu.com/getubuntu/download
I dont have an internet connection where the pc is and I dont actually need to have one. Sorry not very good at explaining things.
You need to buy a license for Windows XP. Go to your local PC shop, they might be able to help you out.
