fingers99 has a good point. Used computers are pretty cheap. A lot of used computers have "missing" software licenses, including Windows (especially people who build their own tend to "keep" the certificate, so that they don't have to buy a new license for their new machine). Find one for sale, then talk the seller down in price, complaining that the computer really isn't worth much if you have to go out and pay $199 for a full license of Windows and other licenses (you don't have to tell the seller that you really don't GAF whether Windows and the apps are on there or not). Talk about how afraid you are that MS will start acting like the RIAA and wipe out your college fund if you can't prove ownership of a license.

Your post spoke volumes to me. About a month after I started experimenting with Linux and dual booting, my computer went stupid on me, and wouldn't recognize my hard drives. It was in warranty, and HP replaced the mobo for free. My wife, a very practical person who saw no need in my "playing" with Linux when Windows was working fine, blamed me and Linux for messing up the machine ("it was working just fine until you started messing with it"). All of our data was inaccessible, yet I had to return the entire computer to HP, knowing that they would completely wipe and reimage the HD. Thanks to Knoppix (and a lot of help from the folks on this forum) I was able to copy to another HD and save our data. So, I ultimately had the last laugh - Linux not only didn't wreck the computer, but actually saved our data when Windows couldn't. If I hadn't "played" with Linux, we would have been up a creek.

Nevertheless, get a cheap computer if you can at a flea market or garage sale. Use your Knoppix disk to test it before you buy. If you can't do that, and you have to use your Dad's computer, for goodness sake, PLEASE do yourself (and your Dad) a favor and back everything up FIRST. You may never be allowed to touch a computer again if you don't.

As for the antivirus, tell your Dad about AVG. It's free and runs on Windows. Personally, I use Norton AV, but I've heard that AVG is very good. Find it at www.grisoft.com