@littlek,
Do you have another computer in the house, and can it burn CDs? If so, you could download the live CD of a Linux distribution, burn it to CD on that computer, and boot if from CD on your computer. (Because live CDs don't touch your hard disk, this would leave your Windows installation unchanged. Just shut down your computer, take the CD out, and you're back at square one.) Where you go from there would depend on the outcome of your experiment.
1) If your screen looks freaky after booting Linux, too, you have confirmed that the problem is with your graphics card. Then your techie-in-law is probably right and you need a new computer.
2) If your screen looks fine after booting Linux, you've got some problem with Windows. If you're lucky, some bug has caused your driver to misconfigure your graphics card, and Linux fixed it when it booted. (It happened to me sometimes.) If you're not-so-lucky, dadpad is right and you have to install Windows from scratch.
***
In case you want to go that route, the first Linux live CD I'd try is Ubuntu (download page
here), the second is Fedora (download page
here).
Whatever you try -- good luck!