OK so my computer for past week been acting really weird.. the internet would go really slow and startup would get even slow.. week later the PC barely startup all the way,sometimes it will but it takes 15 to 20mins to go all way through.. if I got the internet hook up to it, it won't statup up.. if I don't have it hookup,it will boot up all the way.. I scan for virus nothing.. is there away to fix this problem without rebooting the computer? Or maybe a way erase everything without using the reboot discs for it,cause I don't have then

By the way my computer is windows xp

How full is your hard drive? If there is less then 10% left you might need to clean out some files. Also are all of your drivers up to date? After doing / checking that try doing a defrag of the hard drive. Then let us know how its working.

Delete temporary files of your browsing history, but "Preserve Favorites website data."
Do you know how to do this?

Disk Cleanup and Disk Fragmenter
Do you know how to do this?

Have you checked your System Configuration Utility by running, 'msconfig' and unchecking/disabiling any programs in the 'Startup' not regularly using?
Do you know how to do this?

When all else fails, try going back to a restore point before the problem started?
Do you know how to do this?

NOTE: Free programs to consider, Adaware SE, Spybot Search and Destroy, Spywareblaster - all three of these should be used and updated.