You'd have to contact Adobe, but you'd have to start by going to CS6 or later I think: no crossgrades for old versions.
Or consider Parallels Desktop if you don't push Photoshop too hard.
Though I seem to recall there are no discounted upgrades for the student/teacher edition...
This hardware change has the potential to be pretty expensive (you may have to buy a lot of stuff again).
There are no upgrades from old version Student & Teacher Edition to new version Student & Teacher Edition.
But you can certainly upgrade (or crossgrade) from CS5 Student & Teacher Edition (Win) to CS6 (Mac) normal retail product for the upgrade price.
e.g. Photoshop CS5 STE to Photoshop CS6.
Alternatively, join the Cloud for the PS+LR plan @ $10/month.