Today KVM maintainers, qumranet, published the second release of the windows paravirtual network drivers adding support for 64-bit as well as SMP guests. The drivers are designed for windows 2000 and windows xp, however windows 2003 guests will work using the xp drivers. At least kvm-61 is required on the host. The drivers can be downloaded here.

For details on installing the paravirtual network drivers, see the related post on installing windows paravirtual network drivers.

Changelog from official development lists:

Changes from kvm-guest-drivers-windows-1:
- smp support (Yan Vugenfirer)
- x64 support (Yan Vugenfirer)
- prepare for open-sourcing (Yan Vugenfirer)