How to dump my original ROM?

[Eyes-Killer]

Hi,
I want to dump my WM5 rom (I think its from O2). But I'm not sure about that because I've got a G4-type device. :(

If I install WM6.5 on my wizard, can I just undo it by flashing with mine dumped ROM?
I want to know before I upgrade to WM6.5.

cu Floh

[Eyes-Killer]

I think I found the answer myself.

As far as I understand is dumping ROM not necessary since I found O2-WM5-ROM here (I downloaded this and keep it for case if I need to downgrade my device).

cu Floh