Full hardware emulation

Solution 1:

There exist P2V tools to create VM images from existing (physical) systems but so far as I know, these do not take any account of existing hardware. You usually have to manually tweak the produced VM image to use the drivers for whatever hardware the virtualization software provides.

The few virtualization tools I have used offer only a limited palette of hardware options. Given the incredibly vast numbers of distinct hardware products that have appeared in "old desktop PCs" since 1981 it is unsurprising that only a very few of the more common and recent products are emulated.

Unless your application is not a typical desktop application, it won't care if the host CPU is AMD or Intel, it won't care if the disk is SCSI-UW2 or SATA, it won't care if the graphics adapter is an nVidia 8800 or a Radeon 5700, it won't care if the Mouse is a Logitech G9X USB or a MS Intellimouse 1.1 PS/2.

I may be wrong but I imagine it might be more useful to think (and ask questions) in terms of emulation of general characteristics such as overall system speed and graphics resolution. Perhaps if you explain a bit more, people will be better able to provide helpful answers.

Solution 2:

You likely can just create a new VM with a smaller virtual hard drive and a low amount of RAM to get a similar effect.