Win7 WVPC - File access from host extremely slow

Recently upgraded from WinXP x64 SP3 with VirtualPC, which was running
well, to Win7 x64 with Windows VirtualPC environment (running WinXP SP3
guest OS) which has one major issue:

File access from my host PC using (\\host\...) format via Explorer or
via any applications's file open dialog are abysmally slow. It takes
several seconds just to open a folder. Sometimes it's much worse and
gets stuck for a minute or more till Explorer is responsive again.

Opening a file from the host folder is a hit or miss. Several times the
process just hangs, and I end up killing it.

The Host PC's management console shows that the WVPC has accessed the
folder and the file. Is there something I can configure to make the
network access better?

Integration features are not enabled. I can't enable integration
features, because the VPC asks me to login using my domain name, which
doesn't work on the VPC. In fact I don't need domain integration -- all
I need is access to files from the host PC.

Thanks.

--
Himanshu