Pro Tools LE 7.4.3 for Mac Leopard?

I've been using an MBox 2 with Pro Tools LE Version 7.0 on my Mac Book Pro with Mac OS X Tiger. I recently had my laptop stolen and got a new Mac Book Pro but this time with the latest Leopard on it. My Version of pro tools didn't work and was told I had to wait until the new ProTools 7.4.3 version came out as that was the only version that would work. Now it has and I've downloaded it my original authorization code doesn't work with it. Digidesign have just told me that I need to buy Pro Tools version 7.4 again then up date it to 7.4.3 and I'll get a new authorization code and software package. Is this true? Does anyone know anything about this as it seems a bit unfair that I'd have to buy a new version of software that I already have just cos I have a new computer. ANY HELP?????!!!!!!