I want to be able to design and play computer games, such as Counter Strike, Age of Empires, Battlefield, and other games around that genre..

Must Have:

1. Good Graphics Card
2. Nice amount of Ram
3. Nice amount of Disk
4. I would prefer a well known brand of PC's.
5. Monitor size is not an issue, but I would like at least a 17'.

Suggestions please? My budget on this one is about $1200, or would you recommend a custom built PC? If so with what specs and estimated price.

Thanks.