Wow, I'm really uncomfortable making financial transactions over public networks.  But, I'm uncomfortable making financial transactions over my own wireless network.  The risk is probably low, but it's still there.  Most likely, you would be fine, but still makes me uncomfortable.  I really don't know enough about spyware to know whether or not you would be safe.

For myself, I only make financial transactions on my own network at home.  My work network is rock solid, but I still don't do any of that sort of thing there.

A couple of other things I forgot to mention,

In System Preferences, under Security, you can turn on "File Vault" and Set a "Master Password" which automatically encrypts your files such that no one can access your files without the password.  There's one problem, if you forget the password, that's it, there's no saving the data, it's lost.

Also, under the Apple menu, click on About this mac, then more info, scroll down to Software on the left menu, and you will see logs.  There's an installer log.  You can scroll through that to see if there were any unwanted installs on your computer, but you have to be kind of savy to tell whats good and what isn't.