What is the best (PCI Express x16) video/Graphics card?

I have a MSI Radeon HD 2900 XT But I need a better one and my MoBo doesn't support Crossfire/SLI or PCI Express 2.0 so that only leaves PCI Express x16. So what is the absolute best that I can buy for PCI Express x16.



OS: WinXP

Processor: 4.8 gigahertz Intel Core 2 Duo

Mother Board: DG965WH AAD41692-306

Video Card: MSI Radeon HD 2900 XT / 512MB DDR3 / 512-bit / 320 Stream Processors|||PCI Express 2.0 x16 cards are compatible with the older PCI Express x16 slot interface.



HIS H587F1GDG Radeon HD 5870 (Cypress XT) 1GB 256-bit GDDR5 PCI Express 2.0 x16

http://www.newegg.com/Product/Product.as…

System Requirements:

500 Watt or greater power supply with two 75W 6-pin PCI Express power connectors|||check out the Nvidia specs on the link below - and be prepared to uprate your PSU|||ATI

http://products.amd.com/en-us/GraphicCar…

Nvidia

http://www.nvidia.com/object/geforce_fam…





Check Specs for required PSU Wattage