First of all if you have a question related to Open Source, create a new thread &
post it!! The checksum error tells that your ISO image is corrupt. So before you
burn the ISO image to a CD verify the MD5 Checksums. Here is how you do it:
http://www.openoffice.org/dev_docs/using_md5sums.html
In your case you have to download the file again. Also use a good Download Manager
like FlashGet. After the download is complete verify the MD5 Checksums of the ISO
file you downloaded. If there's no error message, go ahead & burn the ISO image in
a CD.