Dell Inspiron 546 with AMD Athlon II X4 Quad-Core 2.6GHz for $429.00 shipped with these steps.

1. Click here to get started.
2. Select to upgrade the processor to AMD Athlon II X4 6520 Quad-Core 2.6 CPU as shown here.
3. Select to upgrade the OS to Windows 7 Home Premium as shown here.
4. Add to the cart and check out as usual.  Here is a screenshot for your reference.

This configuration includes an AMD Athlon II X4 620 Quad-Core processor at 2.6GHz, 2GB RAM, 320GB 7200RPM hard drive, Radeon HD 3200 graphics, 16x DVD burner, and Windows 7 Premium and more.  Note that you might also want to further customize it to fit your specific needs.