I support Quickbooks as a consultant/sysadmin for SMBs.
I have felt your pain. Which is why I wanted to respond when I noticed this part...
And it's compounded by the fact Windows XP doesn't route data over the ethernet as a priority over WiFi connection.
Check out the first set of instructions in http://support.microsoft.com/kb/894564 which should let you set a wired connection to a higher priority than a wireless.
In part, it's due to a severe shortage of computer security specialists and engineers with the skills and knowledge necessary to do battle against would-be adversaries.
Based on my own experience, I would argue that there is a severe shortage of computer security specialists and engineers with the skills and knowledge and desire to do battle against would-be adversaries. Whether it's a personal financial concern or a personal ethical concern, there are lots of great reasons for skilled and knowledgeable experts to seek employment elsewhere.
If it's worth hacking on well, it's worth hacking on for money.