graphic card help

Hello MPGH, I hope that someone can help me with this.

I have a problem with a graphic card that I bought a week ago, since I got it I have been trying to install it following directions from the internet I tried everything, such as deleting old graphic card drivers and disabling it, installing new graphic card and all that, but when I plug in the new card i dont see anything in the screen at all.

this is my computers specs
Processors
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NEW Intel® Pentium® D Processor up to 840 (3.2GHz, 2MB L2 cache, 800MHz FSB) with Dual Core Technology.

Operating Systems
Genuine Windows® XP Home Edition

Chipset
Intel® 945P chipset

Office Suites & Productivity
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Standard:
Corel® WordPerfect®

Optional:
Microsoft Works Suite 2005
Corel® WordPerfect® Office 12
Microsoft Office 2003 Basic Edition
Microsoft Office 2003 Small Business Edition
Microsoft Office 2003 Professional Edition

Memory
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1.5 GB dual channel DDR2-533MHz SDRAM standard, upgradable to 4 GB1 dual channel DDR2-667MHz SDRAM
4 DIMM slots

Drive Bays
Externally available:
Two 3.5-inch bays for an optional floppy or 13-in-1 media card reader
Two 5.25" for CD, CD-RW, DVD or combination drive

Internally accessible:
Two 3.5-inch bays for hard drives

I/O Ports
Video: 1 VGA connector, 1 DVI connector
USB: 7 USB 2.0 ports - 2 front/5 back/1 internal
7.1 Channel Audio: 5 miniature jacks for line in, line out (front, rear and center) and two front panel connectors for headphones/microphone
Network: Integrated 10/100/10002 Ethernet
Optional: One 9-pin serial port (optional)
Optional: 2 PS/2 ports (optional)

Slots
3 PCI slots
1 PCIe x 1 slot
1 PCIe x 4 slot
1 PCIe x 16 (graphics) slot

Chassis
Quiet, silver and white chassis with black accents features:
7 USB 2.0 ports (2 front, 5 back) and front headphone jack
Color coded ports and internal cables simplify service and set up
Dimensions (H x W x D): 17.5" x 7.4" x 17.5"
Weight: 34 lbs.

Power
Output Wattage: 375 Watts
Input Voltage (auto-sensing): 90 to 135V at 50/60 Hz; or 180 to 265 V at 50/60 Hz
Heat Dissipation: 1280 BTU/hour (fully loaded computer without monitor)
Backup Battery: 3.0 V CR2032 coin cell

the graphic card that I bought is a Radeon HD 2600 pro pci express 512mb from VisionTek

Any help would be highly appreciated.

Thank you.

Im using DVI cable to connect it to the monitor and the graphic card is connected to the motherboard.

----------------
1. before I had an old graphic card (ati) not an inboard

2. My ram sucks for windows 7 i have to upgrade that too =(

3.whats PSU lol ?

4. I will get Nvidia if this doesnt work =)

Edit: when I have the graphic card plugged to the computer the fan of the graphic card is working.

My bios is set up to pci thing
but if i have the new graphic card on the computer runs but i dont see anything in display =(

Yes i put in a new graphic card that was recommended to me by dell idiots
and pluged it to the mother boad and connected it to the monitor and i used the DVI cable because thats the only plug that it has.

Dell?
WHAHAHAHAHHAHAHAHAHAHAHAHAHAHAHAHHAHAHAHAHAHHAHA

Its 5 years old

@Hejsan: the fan of the graphic card works when its plugged, ?!

My friend also had this problem,
Uninstall old drivers, look up the name of your new vid card. Install the new drivers for your new vid card. Shut down system remove old card insert new one.
Should work.