I don't run OS X or keep up with Apple products, so I have no idea how well it will run on a 2.83 GHz Core2 Quad. However, that's a good CPU and with 4 cores and 8 GB of RAM, there will be plenty of resources to divvy up between OS X and Windows. In theory, you could split it down the middle and assign 2 cores to each OS and 4 GB of RAM to each.
The concern that I have about the work OS running on top of the hobby OS is not just about viruses and malware. However, it's a good example to start with. As I said above, you will still need to take all of the normal precautions with Windows that you would if it were installed as the host OS. And while OS X is less likely to become infected, that doesn't mean it's impossible. So in addition to keeping Windows security up-to-date, you will need to have security in OS X as well: firewalls, anti-virus and anti-spyware, and regular security updates from Apple.
The problem that I would worry about more is that any hobby tinkering with OS X has the potential to cut off access to the work OS. If you install some driver, software, or update that breaks OS X, you might be unable to launch Windows in the VM. If you are willing to accept that risk, and maybe take steps to mitigate it, that's your call. However, I'm sure that you know your boss is unlikely to be understanding if you say, "I can't make that work deadline because I'm having trouble with OS X."