Problems with PC (HW #4)

I love to do net-surfing, so I often see pop up windows with yes or no question. Some of advertisements says "Free." When I clicked "yes," my PC began to download something. After that, a lot of CM windows appeared. I was surprised and erased all of them. The most terrible thing on PC is spy ware. Last month, my PC began to slow and Windows Me told me that my PC lacked system resources. At first, I do not understand what was going on. However, when I asked somebody on my Japanese blog, a gentleman taught me that the cause might be spy ware. I checked my access records to web, and some strange records were there. My PC sent something to the other, and received something. I was so shocked that I did not realize that it had occurred a month ago. I hurried to initialize my PC. After that, I downloaded Spybot and Ad-aware, and check my PC every night.