People should probably stop suggesting programs that wipe single files or free space. Although this may possibly be better than nothing, it is likely going to leave tons of forensic traces, especially on Windows. The only way to rest easy is to do an actual total drive wipe with something like Secure Erase. I suggest using Secure Erase followed by one pass with random data from DBAN. Then you can feel very confident that none of your data will be recovered. If you delete individual files you will need to worry about all kinds of possible forensic trace evidence being left in various places around your operating system. It just isn't secure to rely on single file overwriting tools, and in some cases it is even worse than others. On Windows single file overwrite is just not secure from forensics, people have been busted in the past based entirely off of trace evidence even when incriminating files were completely overwritten.