It's a real pain. For this task, I recommend CCleaner
, which 'knows' all the main locations, and has an overwrite option. It is not as thorough (or as well-documented) in its erasing as Eraser, but for the vast majority of ordinary users, the ease of use more than makes up for this difference. CCleaner also has a free space cleaning function if you want to be doubly sure.
Eraser comes into its own when you want to erase specific files, or for more in-depth free space erasing. I regard the two programs as complementary, and use them both.