Windows 7 support for UTC time in the RTC is at this time incomplete (July 2013), and not recommended by sysadmins who have tried to make use of it.
The site recommended by grawity above includes a useful summary of the state of this problem.
Currently, if you enable "RealTimeIsUniversal", occasionally the system time gets reset to a wrong time (UTC minus local offset). This causes the DHCP client to fail to refresh the dhcp lease and the system becomes disconnected until you manually refresh the lease, or restart the DHCP client.
Finding a workaround for this particular bug may be an acceptable tradeoff, but there might be other subtle bugs that come and go as Windows gets updated, due to the fact that the "RealTimeIsUniversal=1" configuration is not regression tested at Microsoft presently.