Ideal solution would probably be that server you mentioned, plus an on-call tech to keep it managed for you. You just need an admin who will keep it updated and secure for you mostly. Shouldn't cost you too much extra for that kind of service.
Easy Server Management
http://www.easyservermanagement.com/
http://www.rackshack.net
Intel Dual XEON 2.0GHz
1 GB DDR RAM - 2x120GB Hard Drives
1000 GB Monthly Transfer!
Plesk Server Admin
$299.00/month
$399.00 SET-UP FEE