Can I apply a Group Policy only to systems that have specific software installed?
Answering your question: yes it is possible with WMI filter.
from a nice blog on technet with examples:
example WMI:
Select * from Win32Reg_AddRemovePrograms where displayname = "nvidia drivers" AND version = "1.10"
source: http://blogs.technet.com/b/askperf/archive/2010/06/18/group-policy-filtering-of-installed-applications.aspx