Intel DG41RQ which RAM/GPU to max performance

[davi925]

I have a DG41RQ Intel Motherboard | Intel Core 2 Duo E7500 @ 2.93GHz Processor | 2 GB RAM DDR2 | 250 GB Hard Disk | A 250-Watt PSU |
I wanna upgrade everything other than the Processor & MoBo.
Planning to put in 2 TB Hard Disk as well as a 500-Watt PSU.
So I wanna know if 8 GB Ram can be used or should i go for 4 GB(2 * 2GB).
And What kinda GPU will be compatible with my MoBo to get a good performance of the latest games? And will 500 watts power supply be enough?
Thanks in advance and open to all ideas.

 

[Calvin7]

You can use an 8GB Kit (4GBx2), DDR2-667. I don't think it would be worth the cost, so I would use 4GB kit (2GBx2), DDR2-800.
Kingston Memory Model KVR800D2K2/4GR - $70

Radeon HD 7850
http://www.newegg.com/Product/Product.aspx?Item=N82E16814150656