How to completely clear my computer?

I need to completely clear off my computer because I'm getting rid of it and i can't Find a way that gets rid of EVERYTHING. The computer is running Vista.How to completely clear my computer?
Best way to remove EVERYTHING beyond recovery is to use a kill disk. This will also wipe the OS off the computer for the record. one can be found here http://4sysops.com/archives/free-active-鈥?/a> but there are many out there just search google





Edit: You can reformat the computer or reinstall the OS like other users are suggesting BUT unless you use a KillDisk first or format your computer 35 times, someone with a computer knowledge can recover the data from the computer which may include personal and sensitive data.How to completely clear my computer?
This can be more complicated then simply running ';Format C:'; as everyone has advised you. Did you get a restoration CD when you purchased this computer? Many OEM manufacturers do not give CD Media for Windows Vista, instead using a shadowed partition of the hard drive to obfuscate the installation media directly on the drive. Running ';Format C:'; may destroy your ability to reinstall Vista if this is true. Try pressing F11 during boot up and see if you get to a Vista Installation screen, then follow the instructions to do a Clean Install.





If this is not important to you, then I generally recommend using a Ubuntu LiveCD and running the command ';dd if=/dev/urandom of=/dev/sda bs=1M'; to completely erase the Hard Drive and overwrite the data with random data to prevent it from being restored.
Geez man, all these people have no idea..Even if you ';FORMAT'; it doesn't get rid of everything. Download Fdisk or KillDisk....you dont truly delete until you use a program as such, which can only be loaded on bootup.





Plus all these idiots who just told you to ';format c:';....hmmmmm how the hell are you gonna format c: from windows???....get Hirens Boot Cd includes programs such as Fdisk and KillDisk...any of those can COMPLETELY wipe out your system - even the Feds won't be able to retrieve it for ya. Anyways careful hehe.
Run DBAN, then partition drive, format partitions, install O/S.





DBAN is opensource and also the data destruction software of choice of every Computer Science professor I've come in contact with.
first of all, reinstall a clean copy of windows but as you are installing it will ask if you want to create a new copy or partition... make sure you do format C which means it erases everything
if you have a dell you can do a factory restore which restores the computer to the factory data
you can delete everything off ';C';





go to start.. computer...and right click ';OS(C)'; then hit format....that should work
Format your harddisk(s). There are plenty of internet pages that can help you with it.





Or you can just piss off an angry hacker ;)
The best thing you can do is run a recovery on it that will delete eveything and put it back to manufature setting
If you don't need the hardware anymore... then get a drill and physically destroy the hard drive.





If not, then you could let personal info out.
FORMAT C:
make a clean os installation
Use metho and rub it down till clean
ask a professional maybe there is a reset button
format it.
reformat it!!!!Use the O/S disk if you have...