The virt-manager says, on the first screen: "[choose] whether the VM will be fully virtualised or para-virtualised" But there is no option for this.
The choice for paravirt/fully virt in the wizard is hidden/skipped) if the CPU in the host system does not support the AMD-V or Intel-VT extensions required for fullyvirt. Perhaps we should either clarify the language in the first page to add this not about fully-virt only being available with hardware support, or perhaps show the option screen of the wizard, but with fully-virt option disabled.
The first option is better, and it would be good if the skip was shown, but greyed out.
In latest upstream code, we always show the step with the para/fully virt choice. On systems not supporting fully virt, the fully virt option is disabled, and an explanatory note is displayed telling the user they either have no CPU support, or it is disabled by the BIOS. http://hg.et.redhat.com/virt/applications/virt-manager--devel?cs=8cc9ccf3bfb4 Will get this into an FC6 errata
virt-manager-0.2.6-1.fc6 has been pushed for fc6, which should resolve this issue. If these problems are still present in this version, then please make note of it in this bug report.