I'm confused. What Windows emulator? I don't know of any.
In order to get updates in XP, go to Control Panel->System which will bring up the System Properties dialog. Select the "Automatic Updates" tab and setup automatic updates. Once you do that you'll start receiving updates.
As a test, I setup a new VM and installed XP Home on it. I then enabled Automatic Updates and within a matter of minutes had several updates to install. A while later another 125 updates. Later there were more updates. So far my XP VM has received more than 200 updates.
BTW, what version of Win 7 did you install on your Mac? If it is the Pro or Enterprise version then you can download and install "XP Mode". XP Mode is actually a VM running XP within MS Virtual PC but there are several advantages to it over the VirtualBox route, not the least of which is that it includes a fully licensed version of XP Pro.