I have OSX Leopard running on my HP Pavilion a6245n, and running well. I also have it running on my Laptop, a dv6000.
Would it be possible to purchase the Snow Leopard upgrade disc and install it, and would it work correctly? Will I have to re-install my drivers and the like, because I don't even remember where I got them, or what fixes I have used.

You should be able to, but don't hold me to it. You can buy the disc from Apple Store for £25. Failing not being able to upgrade, you can install using Chameleon DFE (I think thats what it is called)

Seg

I purchased the upgrade disc and it says I cannot upgrade due to the fact that my Leopard install doesn't use the GUID partition or something like that. Not sure what to do.

I've read something online on a way around this, will try it and report back,