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The best way to upgrade would be to copy the existing store file to a different account on a development domain, copy the database to a development database, update this development database to use the new development domain, update local.xml to use the copied database, and upgrade via SSH using these commands from the document root of the copied store
tar zxvf magento-184.108.40.206.tar.gz
cp -pvr ./magento/* .
cp -pvr ./magento/.ht* .
rm -rf ./magento ./220.127.116.11.tar.gz
rm -rf ./var/cache ./var/session
This will extract the 18.104.22.168 files over 1.4.x.x and commence the upgrade process once you load the development domain in your browser.
As always, be sure to back up your files and database before any changes are made. Good luck!