OK, so I'm planning on upgrading my inspiron 530s to a new case, new power supply, and new graphics card. I already bought the Nvidia 9600gt and now I just need a new case and power supply. My current case is a slim line with a crap power supply, so that's why I'm upgrading.
The power supply you picked, the Apevia 500w is a low quality power supply, i wouldn't use it in ANY build, the case you picked the Rosewill is a decent budget case, but comes with it's own power supply, also a low quality unit. A decent power supply for your system and a 9600GT would be this Silverstone ST 400w unit ( it's not just watts you need, it's also AMPs and quality) for $30 after rebate http://www.newegg.com/Product/Product.aspx?Item=N82E168...
a higher quality unit is this Corsair 400w unit for $50 after rebate. http://www.newegg.com/Product/Product.aspx?Item=N82E168...
There are a number of decent budget cases for sale between $20 - $35
To recommend a CPU we need to know exactly what model you have, including what motherboard, the 530s has different options.
Windows Version Microsoft® Windows Vista™ Home Basic
Model Intel(R) Pentium(R) Dual CPU E2140 @ 1.60GHz
Drive Size Free Space Utilized
C: 222.78 Gb 158.22 Gb 29 %
D: 10 Gb 5.02 Gb 50 %
Intel(R) G33/G31 Express Chipset Family 320 Mb
I was able to install a E5200 on a HP system with the G33 motherboard without a BIOS flash, the Silverstone ST400 power supply listed was used in a Toms Hardware system builders marathon several months back and worked well for them. Good luck, it's a good upgrade.