Low budget upgrade needed .. 10K Budget

Hi , i need to upgrade some components of 1 of my office's PCs. Need upgrades for the HDD , RAM , MoBo and Processor.

The PC has a 9400GT . Purpose of use is mainly 3D modelling.

The config i have in mind is as follows :

AMD Athlon II X3 440
Asus M4A78LT
4GB DDR3 ram
Seagate 500GB

If possible please recommend a better config for around 10K.
Please note that these are all the components im looking to upgrade at the moment.

Thanks