You have quite a few choices to run Leopard (10.5) on Mac hardware:
Any Mac that shipped with a minimum version of 10.6 and higher will be unlikely to run well on Leopard as the drivers needed are usually in the builds listed in the right column of the list above.
So, for official support - you have the following Models:
- Mac Pro, Mac Pro (Early 2008) and Mac Pro (Early 2009)
- Xserve (Early 2008) and Xserve (Early 2009)
- iMac (Mid 2007) through iMac (Mid 2009) inclusive
- Mac Mini (Mid 2007) and Mac Mini (Early 2009)
- MacBook Pro (Mid 2007 - a.k.a. 2.4/2.2 GHz) through MacBook Pro (Mid 2009) inclusive
- MacBook (Late 2007) through MacBook (Mid 2009) inclusive
- MacBook Air (Early 2008) through MacBook Air (Mid 2009) inclusive
For storage needs, you might not want to waste time trying to run Leopard virtualy under a newer OS since the drivers want to be installed on the final OS in almost all circumstances.