Atom CPU has very low performance. Its best feature is power-saving. That is why it is so popular in netbook market.
If you use it for auto cad -2d, Atom CPU should not be your choice.
If you have $2500 - $3000, consider to buy DIY computer with:
- AMD Athlon II X2, X3, X4 CPU.
- AMD 785G All-in-one Motherboard
- 2G Ram or more
- 500 - 1000GB Hard Disk
- DVD Writer
- OS not included