It has nothing to do with the version of the OS needed to run a particular software program.
Rosetta is a emulator that allows 'non-intel' compatible software to run on an 'Intel' Mac. In any case.you should be able to 'downgrade' the OS to 10.5.7 or 10.5.8.but of course you will need to purchase a copy of 10.5 Leopard.but that's going to cost $100-$130 bucks! if you have the newest 13' MacBook Pro.it originally shipping with OS 10.5.7.but since you just purchased yours 3 days ago, it probably shipped with 10.6 or 10.6.1.
Click to expand.First of all.the software you purchased.if it it not compatible with Snow Leopard.then it's not compatible! Trying to launch the installer program in SL won't help.