Posting in the Magento forums has been disabled pending the implementation of a new and improved forum solution which should better serve the community.
For new questions please post at magento.stackexchange.com, the community-run support site for the Magento community. We will be providing updates on the new forum solution soon. For questions or concerns please email email@example.com.
Easier would be to have two dedicated servers. One will host the PHP installation of Magento, and apache, with the virtual hosts regulating both domains. The spare server can then be solely used for MySQL, totally optimized to just be a dedicated database server. That way, you get fastly superior performance. You can of course still have separate IP addresses for each domain if required.