My experiances with viruses

My experiences with viruses have been tremendous, I recently had an attack on my computer and I had no idea it had happened, I was on my computer one day and I saw a pop up for a virus that had been detected and it had to be stopped with a product called Virus Melt. I had no idea that it was even a fake program designed to get me to put up information about myself and my credit card information. Thinking that this software was a good thing to have I put in all of my credit card info and I noticed it did not work but that my computer was slowing down to the max. I had no idea what to do but I think I got lucky and I decided to look for information about how to get rid of virus melt completely. I had to take out some of all the files that it had self downloaded on my computer. I also downloaded the Norton Anti-virus software to take care of the virus. It did a great job of getting all of the junk off of my computer but I notice that my computer is still slow and has a hard time running because of the damage it caused.