haha
You guys don't understand viruses, do you? They aren't going to be obvious. The point of a good virus, is to keep it hidden. You won't notice till the day you put in your cc number, or the day he decides to open your keylog files and get every account/password you have typed in.
If it's a rat, he could even just click a few buttons, and have any saved password on your browser, or even watch your screen. And he could be doing all this without you even noticing.
So just because nothing is different, doesn't mean you aren't infected.