Absolutely! Especially if your base content doesn't change much.
Primary: XHTML for base content. - "Always" online!
Secondary: OsTicket, PHPBB3. - Ticket Troubleshooting, Self-Help.
*Tertiary: WP for blog. - General & personal communication.
They're easy to tie together to give the appearance of constant flow within your site. If the database goes down you still have your "Main Site" (which is your primary consideration) with all necessary information (email, phone, address) for current or potential clients to get in touch with you. The only time your site would appear to be "down" is during a server reboot - unlike sites that require database connectivity or larger server resources to function which is the main point of failure in a server environment.
*You stipulated in your original post that your primary concern is for your computer business, that's why I relegated a blog to a tertiary status. I'm not suggesting that you're boring by dropping it down the list.
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