I have two suggestions-
One:
If you want to keep your PC clean and dont want to bog it down go to portableapps.com or liberkey.com both install on on a flash drive and dont leave anything behind when you exit. (except for the flash dive boot up logs) I can use Ccleaner, registry, defrag tools, run Linux, p2p, IM, open exel or word files and more start a web or ftp server and best of all you dont need a flash drive- you can install it to a folder on any drive, hell it can even run a web server off a cd( (cant update it though (cant hack it either)) lol.
If you do put it on a usb stick its a bit slower but goes to any pc u put it in. Firefox with favs etc goes with you.
Two:
Download midget porn its a much smaller DL