Store not working when installed in VirtualBox VM

I can't get the store (or app updates in the store) to work with my Windows 8 Pro installation in Oracle's VirtualBox. Anyone know what I can do? I tried the default NAT setup. Then tried Bridged Adapter (and promiscuous all), but still the store gives an error message (or the apps just go to Pending and never change). Any ideas would be most appreciated.

Actually, the store is working (kind-of) but VERY SLOWLY! After a full day, it installed one app update! I think. The apps do go to pending, then (sometimes) downloading, then (usually) an error message saying it failed to install. Any ideas?