Oh were it that simple!
There are loads of track left that will show where you've been and the only way to get ride of them is with a tool designed to do just that. For a free fairly good one try Windows Washer, but there are many others.
As an example, if you frequent newsgroups of a dodgy nature, even if you never subscribe to any, try doing a search on your C: drive for .dbx files, you may have a little surprise!
I used to do PC software audits for a living, it's sometimes surprising what you can find if you know where to look.