How Can I Achieve 99.99%

We have a site that almost almost almost hit 100,000 page views last month. We do a fair amount of eCommerce and also use web-based customer management software. Because of this, we require fairly high uptime - in the 99.99% range.

I've been checking out options like RAID, hot-swappable power supplies, and redundant network cards, none of which our current host has. But then I realized that next to none of the recent performance issues we'd had were related to hardware - they were all related to someone else on the shared server writing a script with an endless loop and taking down the server until someone noticed and restarted Apache.

I'm a programmer and have admittedly very little experience in actually running a server. But I would think it would be relatively easy to write a script that checks the server load every few minutes, restarts the offending service or terminates the offending process, and emails a tech to check the logs later.