|"i can,t download any thing cause it says not enough memory"|
Are you sure that's what it said? Could it be that your hard drive is almost full? Hard drive storage space & memory are 2 completely different things. Before going to the extreme of wiping your drive & starting over, try dumping some of the uselss crap, uninstall unneeded programs, & transfer your important files (pics, videos, music, word docs, etc) to CD/DVDs or an external hard drive.
Start by installing CCleaner-Slim. Start the program, make sure "hotfix uninstallers" is checked, then click Analyze. How much will it remove? My guess is a LOT. It's safe to remove everything it finds - just click Run Cleaner.
You should also click Tools > Startup then look at which programs are preloading in the background when Windows starts. There are very few that are absolutely necessary & you should be able to identify every single one of them. I've already cleaned up my Startup list (currently using my laptop) but to give you an example, all I have left are entries for the audio, graphics, touchpad, & anti-virus.
Running MSCONFIG is another waay to clean up the startup list: