If it's a snow leopard disc, your license covers installation on one machine only unless you bought the family version.
I would follow the Tiger guide on Mecdrew's site to make your USB installation key.
I wouldn't recommend, or want to be responsible for trying to upgrade a MBP that works fine with Tiger to Snow Leopard myself. I wouldn't recommend an upgrade strategy from Leopard either for that matter.
Your best course of action when going from one version to another (Tiger to Leopard or even to SL) is a fresh install, not an upgrade.
Mini 9 | OS X 10.6.7 | NBI 20100616212351| BIOS 05 | 32 GB Runcore | 2 GIGS RAM
10V | OS X 10.6.7 | NBI 20100616212351 |BIOS 06|160 GB|1 GIG RAM| 6 Cell Dell Battery
Back up Mini 9| OS X 10.6.7| NBI 20100616212351| BIOS 05 | 32 GB SuperTalent | 2 GIGS RAM