Cache and memory wiper software for PC?

http://www.filehippo.com/download_ccleaner/

ccleaner has a file shredder option. As does spybot both free.

You shouldn't need any additional software, period. Just read the PC's User Manual to learn how to return your PC to Factory-New condition. And, learn How to BURN your Windows Recovery disks as well, if you haven't already done so. Nobody should ever accept a used PC, for free or PAID, without these ESSENTIAL disks being included.

There are a lot of issues to consider. Unless you are very technically minded it's hard to remove all personal information from a PC and make it unrecoverable. The best methods are either nuke the hard drive then reinstall the operating system or else fit a new hard drive. http://download.cnet.com/Darik-s-Boot-and-Nuke-for-CD-and-DVD/3000-2094_4-10151762.html - need to have some technical ability to use this and reinstall OS from scratch. If you use any other method to wipe your personal files you also need to wipe old system restore points. If in doubt - once you think that you have removed everything that you need to remove run a scan with http://www.piriform.com/recuva and see if it finds any recoverable files. Also consider scanning with: http://www.osforensics.com/discover.html There is information hidden within Windows system files that isn't readily available to the average user but if you're paranoid nuke your hard drive.