This is not a problem. IPmonitor is not very process intensive.
One consideration would be reassigning the HTTP/HTTPS ports from twithin the Configure IPMonitor Utility -> Start-> Programs-> IPMONITOR -> Communications; Web Server Ports - (required for login, needs to be different from what Orion is using in IIS)
We would advise you to always install eval software on a machine separate from your production machine.
However, if you have no choice, there is no inherent reason this would not work. Just make sure that you configure ipMonitor's web server on a different port than Orion's.
Installing Orion and ipMonitor on the same box won't have any conflicts other than (hosting) web ports. ipMonitor's SSL port will fight for Orion's, unless you disable SSL for ipMonitor or change the port in its configuration program.
You can do that during the install when it displays the ports it will bind to (it's easy to miss because you're more than likely wanting to click "Next").
Other than that, I think the regular advice would come into play: Keep an eye on the production box (yourself, with Orion or with ipMonitor). ipMonitor will record its statistics on the drive you install it, but the storage rate is very reasonable.
I think there is an echo in here.....