Download the full SP2 package to your computer from the link below and then install it.. (It's a large file, about 266 MB, so make sure you have a broadband connection.) If you can't download the file to your computer, then find a friend or family member with broadband and a CD burner, then download and burn it to CD, then transfer it to your machine.

http://www.microsoft.com/downloads/details.aspx?familyid=049C9DBE-3B8E-4F30-8245-9E368D3CDB5A

If "Chkdsk" found problems, it's also possible that your hardrive is headed south.. Be sure to make backups NOW.

Hope this helps.

Grif