How can i reset my computer?

hey, my computer has really slowed down. I am using windows xp, and nero back it up. all of my stuff has been backed up on cds, but I dont know how to reset my computer and then back it up so its good as new. any ideas?

To quote The IT Crowd- Have you tried turning it off then on again?

DEFRAGMENT!
then download dustbuster xp and run it. If you can't figure out how to find the program and download it I suggest you take it to a computer repair service.

not helping how do i use nero back it up

The only problem with backing up now is you will also backup the problem you originally have. More than likely your registry is gummed up I suggest you uninstall any extra programs you have running at start up install and run Ad-aware 2007 from lavasoft (free) and a program called Regcure ($) And do a little system maintainance. any advice on Nero needed I suggest you contact Nero customer service and ask an expert on the software.

that or you can make a copy of your documents you want to keep, have a list of programs you have + their serial numbers if they require any and reinstall windows or whatever OS your using.