Need Graphics Card Help

Hi,
I need some help choosing a new Video Card for my old PC. It's an HP d1000y (all specs listed below), that I ordered from Comp. in early 2005. I had always meant to upgrade the Video Card, a 256MB ATI RADEON X600, but never could afford to do so until now. When I went into the market I was hit with so many different kinds of cards, I am lost as to which one will work with my system specs.

I'm fairly good at using a computer, but pretty much an illiterate when it comes to the tech side and how they work.

I am looking to upgrade so that I can run high end photo editing graphics software like Adobe Photoshop Extended CS4 / Flash, a 26-28 inch flat screen monitor, and also play high end games like COD4, Half Life 2, World In Conflict, Crysis smoothly.

I have one PCI-E port for the video card, and 5 regular PCI ports (two are unused).

My power PSU is 400w. I will probably upgrade to 750W.

Also, should I upgrade my CPU? If so, what would work with my motherboard?


Any help would be greatly appreciated, and I thank you very much in advance.


____________________________________

System OS = Windows XP Pro SP3
System Make = HP Pavilion 061
System Model = PU031AV-ABA D1000Y

Purchase Date = 2, 2005

Main Board Make = ASUSTeK Computer INC.
Main Board Model = Puffer2
Main Board Version = 1.xx
Main Board BIOS = American Megatrends Inc. BIOS Date: 01/23/06 20:09:06 Ver: 08.00.10 A M I - 1000623 20060123

Processor Description = Intel Pentium 4 w/ HT Technology, 3.4 GHz
Number of Processors = 1
Processor Clock Speed = 3400 Mhz

Performance = 320 GB RAID 0 (2 x 160GB SATA HDDs)

Graphics Description = 256MB ATI RADEON X600PRO w/TV-Out & DVI

Memory Installed = 3072 MBs
3 GB DDR2-400 RAM / PC2 3200 (2 DIMM)
Memory Slots = 4 slots
Memory Configuration = 512+1024+512+1024;DIMM Synchronous

Sound Blaster Audigy 2 ZS

Drive Name (C) = HP_PAVILION
Drive Size (C) = 298983 MBs
Drive Format (C) = NTFS
Drive Name (D) = HP_RECOVERY
Drive Size (D) = 6169 MBs
Drive Format (D) = FAT32

DVD-RW Model = HP DVD Writer 640b
DVD-RW Read Speed = 7056 KB/sec (40X)
DVD-RW Write Speed = 7056 KB/sec (40X)

DISPLAY = ATI Technologies Inc. RADEON X600/X550 Series
DISPLAY = ATI Technologies Inc. RADEON X600/X550 Series Secondary

bttt