Windows antivirus

Good afternoon,
I've just installed Parallels on my wife's Mac Book Pro. I had previously installed Windows XP through Boot Camp, in order to run Quicken Home and Business. We use this program for a small business, all of our invoices and accounts are established. Now that I have parallels up and running, and am able to access Quicken without rebooting, do I have to worry about virus' populating the windows side? We do not access the net from windows, nor do I have automatic updates active. We just use the Windows side to use Quicken.

Thanks in advance