The quick answer is to keep searching for an XP laptop.
If you are running Win7 Home then my suggested reading may not help (Win7 Home has all sort of useful stuff disabled/not-installed) - but do have a look at them.
Can you divulge what app you are trying to run? Compatibility mode normally copes pretty well with even very old stuff. You may be able to get it to run in DosBox (q.v.)
Send me a PM if you don't want to air it all here.
Mac :-)
Edited to add: Checkout
https://blogs.msdn.microsoft.com/vir...home-editions/