How insecure is a Windows HVM?

If I have a Win 7 HVM in Qubes which is PVH, can apps in there affect the system if I got a virus or other while using Windows? Or can I just delete that HVM if there was a virus.

I searched, but I was finding answers about dual-boot instead of HVM.

Is it much better if I kept Windows on a separate laptop?

if so, why is even qubes secure at all
qubes secure is because compartmentalization, it separate lot of thing, if you got a dispvm (or appvm) infected, just restart it
with hvm:

(except when you’re so unlucky that you infected with xen exploit, it game over™)

Yes, PVH should make it as isolated and secure as currently possible with Qubes OS. See details: