Hi,
I actually wanted to know if the upgrade from the apple store would work with my current OSX as I don't want to fork out £130 for a new one.
Cheers
Sorry, I didn't make that clear. The Snow Leopard 'upgrade' disk is just a normal disk which can either do an upgrade or a full install. It is technically capable of upgrading Tiger, but because of the rather large differences between the two OS's, you may run into problems (which is partially why I recommended a fresh install).
This was covered a while ago by Engadget I believe; they upgraded a system from 10.4.11 to 10.6.0 and it worked, but there were a few broken apps and processes. That's partially to be expected anyway, as 10.6.x breaks a lot of Leopard and Tiger apps because of the rather extensive re-write of the underlying codebase (you might run into this even if you fresh install, as some apps will only update so far before you have to buy a new version), but it is possible to achieve.
Rather than being a technical issue, it's more of a moral and legal issue. By installing Snow Leopard using the upgrade disk on a Tiger machine, you're technically breaking the EULA, as it states it needs to be installed on a machine that had Leopard on it. What that actually means is that, by only paying £25, they want to ensure you either own a licence for Leopard already through a Mac that came with Leopard, or you already bought Leopard separately. Seeing as you haven't, installing Snow Leopard with the 'upgrade' disk is a violation of those terms.
What this means in practice as far as I'm aware is negligible, as Apple has no way of knowing their end if the machine you have ever had Leopard on it, nor can they possibly be aware if you own a licence for Leopard, so frankly, there isn't really a reason not to just use the 'upgrade' disk. That said, it's nice to know all the facts to make an informed decision!
