diff -rup virtinst-0.200.0/virtinst/Guest.py virtinst-0.200.0.new/virtinst/Guest.py
--- virtinst-0.200.0/virtinst/Guest.py	2007-07-18 22:04:21.000000000 -0400
+++ virtinst-0.200.0.new/virtinst/Guest.py	2007-09-06 23:11:54.000000000 -0400
@@ -151,9 +151,7 @@ class VirtualDisk:
                 ret += "      <driver name='%(name)s'/>\n" % { "name": self.driver_name }
             else:
                 ret += "      <driver name='%(name)s' type='%(type)s'/>\n" % { "name": self.driver_name, "type": self.driver_type }
-        if self.path is None:
-            ret += "      <source %(typeattr)s=''/>\n" % { "typeattr": typeattr }
-        else:
+        if self.path is not None:
             ret += "      <source %(typeattr)s='%(disk)s'/>\n" % { "typeattr": typeattr, "disk": self.path }
         ret += "      <target dev='%(disknode)s'/>\n" % { "disknode": disknode }
         if self.read_only: