[Users] Change virtual disk interface

[wdh at dds.nl]

I have serveral "old" KVM virtual images, all off them using virtio  
for networking and disks. Trying to import these into my EXPORT  
datastore ends up with an error:

  virt-v2v -i libvirt -o rhev -os 10.0.0.3:/nfs/export  -n br0 PXE5-test
  PXE5.img: 100% [=====================================================]

  virt-v2v: WARNING: Unable to convert this guest operating system. Its
storage will be transfered and a domain created for it, but it may not
operate correctly without manual reconfiguration. The domain will present
all storage devices as ide, all network interfaces as rtl8139 and the host
as x86_64.
  virt-v2v: PXE5-test configured without virtio drivers.

How can I avoid these errors?
How can I fix this error.

After restoring the image, I am able to change the network interface  
from rtl8139 to Virtio. However; I cannot change the disk. In the  
admin console going to Virtual Machines --> <virtual machine> -->  
Virtual Disks --> <disk> --> Edit gives a menu, but the only option I  
can change is "is bootable". Options  like "Interface" are grey and  
cannot be modified.