Leopard won't burn my DVDs

I have just upgraded to Leopard today on my PowerBook G4 1.5GHz, 1.25GB. Have not tried it out fully yet but my first impression is it seems to be slower than when I was on Tiger? Is it just me or can that happen on a G4? Sure my PowerBook is fast enough for the Leopard... Also when I burn a DVD, it can burn but when it gets to the end of the verifying stage, it says the disc cannot be verified... I tried 3 DVDs, the same probs. I then tried a CD, no probs. I then tried using Toast 9 with a DVD, no probs too. So any idea why Leopard won't verify my DVDs? They are DVD-. I certainly don't want to having to reinstall everything again...

Add more memory to the G4. Leopard is larger than Tiger and needs more memory for best performance.

As for the DVD problem, I've not had much luck with DVD-R media. Try DVD+R instead and see if they verify correctly.

Regards.

If it is the 12" Powerbook then he already has the maximum amount of RAM installed. I have the same one and yes it is slower under Leopard than it was with Tiger.

Yeah, it is a 12" PowerBook and it's the max capacity I can get unfortunately. So is it worth of downgrading back to Tiger then? As I said I have not tried everything yet, I mainly use CS3 apps and my friend, the real Mac head keeps saying CS3 works better on Leopard and faster..... any comments?