Nvidia With ATI Is It Compatile??

Hi All I Want To Upgrade My PC Here Is The Config Of My PC

OPERATING SYSTEM
Windows 7 Ultimate 32 Bit

CPU
AMD Sempron 140
Sargas 45nm Technology

RAM
2.00 GB Single-Channel DDR2 @ 267MHz (4-4-4-12)

Motherboard
ASRock N68-S (CPUSocket)

Graphics
256MB GeForce 7025 / nForce 630a (ASRock)

Hard Drives
1863GB Seagate ST2000DL 003-9VT166 SCSI Disk Device (ATA)
233GB Seagate ST325031 8AS SCSI Disk Device (ATA)

My Graphic Card Is In build In My Motherboard


Now I Want To Upgrade My PC I Want To Put An AMD/ATI Radeon HD 6670 GPU 1 GB DDR3 Graphics Card. Is It Compatible Because Mine Is DDR2 Ram And Also Is My Motherboard Compatible And Will It Work Properly
Also Want To Know That Do I Need An Extra Power supply For This i.e New SMPS??


Also Suggest Me Some Good Graphic Cards Under 5000 INR or $90 to $95


Thanks In Advance