Can someone please clear something up for me???

In most animals the karyotype for a female is 'XX' and the karyotype for a male is 'XY', yes? This is why, for the most part genetic diseases show up more prominently in males as they are usually on the X chromosome, which males only have one of, and females are usually carriers...

Ive been doing some reading and lots of places seem to say that the sex chromosomes in budgies are reversed (ie. Female = XY, Male = XX.) Is this right? Because I'm just a little bit confused... is it a bird thing?

Yes that is correct. Female budgies are XY (also sometimes shown as XZ) and Males are XX

Thanks, I suppose it makes sense... After all, generally in birds the males are the fairer sex and so need more room for genes...

All birds are like that.

The chromosomes are actually called ZW.

This I would say is because both mammals and birds come from reptiles and reptiles don't all rely on chromosomes to determine their sex.

It is only mammals that have XY for males and some insects too. Birds have XY for females. Some reptiles have both chromosome and temperature determination. I am not sure on amphibians and fish. I know some species of fish can change sex later in life.