I remember from your other thread about case airflow and fan setup.
My first priority would be to get a new PSU. For the X1950GT, I would look at the Antec Trio 550w or the OCZ GameXtreme 600w. I don't know of any stores in Malaysia, so I will leave that up to you.
If you get one of those PSUs, you can easily get get an X1950GT or even a 7900GS or 7900GT. Those will be a good upgrade.