[TYPO3] Help - Upgrade gives error - The requested URL /index.php was not found on this server.

[Jeff Segars]

I'd suggest checking out the upgrade page at 
http://wiki.typo3.org/index.php/Upgrade for details of where all the 
symlinks should point now.

Your .htaccess file should be OK as it is since there will still be an 
index.php file in the root of your site.  The only difference is that 
file is linked to typo3_src/index.php instead of tslib/index_ts.php

Thanks,
Jeff