need to format

[stevenweight]

how do i reformat from boot up on a dell dimension 2400 as some one has put a newer version of xp on and i dont have that disc

 

[lon0]

I assume you're asking how to install the newer OS again on top of the one currently there? If there is no recovery partition installed then without the XP disk you cannot do this. You could run a system restore if you are having problems but don't want to completely reformat
http://support.microsoft.com/kb/306084