Yup DOSBox. But why doesn't your PC have install disc/s. With most manufactured PC there is a Utility to Create a set of System Discs and with some, like Dell computers, you can create the Real OS install DVD or ISO to burn to DVD or USB thumb drive.
The client I'm working with apparently never utilized the create system disks option. The machine in question is a late model HP with the appropriate Win 7 MS decals, so I would assume it's a legit OEM licensed unit, just some laziness or lack of understanding during start up I suppose. The machine has been in use for a matter of months so I'm not clear if a proper system disk script could run at this point. Perhaps it could. Not sure, and both of us are extremely limited for time and I go on the road in a new job in a matter of days. It's an "accomplish x hours of _______ in x minutes" scenario at this point.
I'll see how DOSBOX behaves. If that fails, I may have to take a run at making system disks. I'm test running this project on my own Win 7 machine to save time at the client's home.