I assume U have your data saved. Ok, let's see. Clean install.
This is so U could format your hard drive first via Recovery console, then try to reinstall Windows.
Put Win XP cd in.
Change boot order in bios , so that cd rom is first boot device.
Press R key, as soon as you see the message "Press R, bla, bla,bla.........."
Type Install number (usually U just press 1), type password, or just press Enter if U don't have a password.
Welcome to Recovery console!(cmd)
I don't know if you use cmd, so, here:
To format, type this command:
format C:\ /Q
or, if U want a certain type or drive, U can see all options by typing:
format /?
Usually, used are:
format C:\ FS:FAT32 /Q, or
format C:\ FS:NTFS /Q
U can choose any type of compression, and the Q stands for quick format, bla,bla,bla....
After done, U can check if the drive is empty by using the dir command
After, restart, and normally reinstall Windows.