answer:How big is your hard drive? On an older computer that only has 40GB, that is normal; in a newer one that has 320GB-1TB, it’s a bit different. First, find out what the cruft is; download something like WinDirStat to find out what it is that is taking up space. Maybe it’s something simple, like a newly installed app creating log files hither and yon, maybe your LOLcats video collection is huge. I can’t say without a little more info, but I would not automatically assume infection either.