hi, the best program to use has been given - Eraser, however the link given is old, the software was sold afew years ago to Heidi. you can get a newer version at the link below.
http://www.heidi.ie/eraser/
make sure when you download any file (pictures) it's to the place you want to keep it. if it's not and you move the picture from where it's downloaded an image will still be on your HDD, but it wont be allocated on the HDD table so, in effect, it's the same as deleting the file from the recycle bin.
you can use Eraser to clean free space (where files from the recycle bin go) by opening Eraser and right-clicking on a free part of the page, then select "new task". on the drop-down menu select local drives, make sure "Unused space on drive" is selected, then click OK. it should appear on the page. highlight your new task by right-clicking then click on "Run" Eraser will then clean all the things you have deleted from your recycle bin and anything else that's been deleted. run it overnight as it will take afew hours.
you can delete things with Eraser by right-clicking and selecting eraser, the default times it over-writes is 35 times, that should be secure, but you can change it to as many times as you like.
your ISP keeps records of the places you have been, you can use an anonymous proxy to hide from your ISP. an encrypted connection will be made to the proxy. and your connection will go through afew servers at the proxy's site. the proxy host wont know your traffic from others using the service just all the end connections made. one downside though is your connection will be slower because it is traveling farther. here's a good free anonymous proxy. it's abit difficult to set up though, but if you search you will find instructions. there's a forum too.
http://anon.inf.tu-dresden.de/index_en.html