To use your dual core processor properly, like everyone else is saying, you will need more money.
As well as the (expensive) dual core chip, you will need a semi-decent mobo, some decent RAM.
Then you have the HDD, DVD drives, case, PSU, gfx card etc
Simply get more money, or revise your specification of dual core.
There is simply no point in spending on a dual core then the rest of your components not being up to scratch to actually use it!