Depends how different the hardware is. You've effectively got the problem of moving a hard drive to a (number of)different machine(s). This sometimes works - ie, XP boots and sorts out the driver issues (usually after a number of reboots) - sometimes doesn't (then repair reinstall will usually fix it - but you've effectively lost most of the advantage of imaging if you need to do that). If motherboards use same chipset, think that's definite advantage.
I'd also run sysprep on the machine to be imaged before imaging (so each imaged machine will run a mini-setup when you start it - detects plug and play, you can supply the XP key for that machine, machine name, workgroup/domain, gives it new SID).