Problem with PowerColor HD 4850 512mb

I Got my new graphics card yesterday, i used to have an 8600GTS installed. I have already removed Nvidia drivers an removed old card which i replaced with the 4850 card. I get to my desktop and it detects new hardware and asks me to install new drivers. So i do with the drivers disk. once i installed ATI drivers and CCC programs etc. i restart my computer. My computer boots up and then starts loading XP. This is where it goes wrong During when XP loads after about 10 seconds the screen goes blank and a message appears on screen saying that the monitor has lost signal and goes into standby mode. My computer sounds normal and everything and its all still working like it was before the screen went blank. Ive checked inside to make sure its all connected properly and ive went into safe mode and uninstalled the drivers and downloaded drivers from the catalyst website. The problem still happens with these drivers. Can anyone Help me? Ive tried everything deleted everything Nvidia related erm.. installed one driver at a time by restarting and installing the next bit. Still no luck If anyone can help id be Most greatful!

My specs are in my sig but if u carnt see my sig its,

AMD 6000+
M2N-E mobo
EZCool 600W PSU
Corsair 2GB XMs2
PowerCHD 4850 (obvs)
DVDRW

Notes:

This is my First Graphic card upgrade
The New Hardware detected message carnt find software or read the disk. I have to manually click on disk drive or let the disk automaticly run. I did get it to search Disk drive etc. still not working also the message doesnt like to leave me alone lol. unless i Click cancal three times.

Well on the requirments it says 450w for a single card and 600w fo Xfire. It does display a picture the problem only occurs when i install the drivers really. Nothing else my brothers convinced its a software issue i dont know. I made sure the power supply is properly connected and everything. Still nothing :S thanx tho anyway

it may actually be the psu. i've never even heard of EZCool, and from what i found on google, it doesn't sound like the best psu brand you've ever seen. it may not be delivering as many watts as it says it is.

I dont know what would be causing that

One solution to your problem would be to just do a clean install of xp on your computer (im not sure if that is something you are interested in doing or not). If it worked after a clean install then it would most certainly a software issue, if it still wasn't working then it would have to be a hardware issue (maybe it isn't getting enough power like nik_I sugested)

Again sorry to ask but you have to start with the basics. How did you go about removing the old nvidia drivers?

Hi again guys I have Fixed the issue i had found out that i delted the Nvidia Chipset drivers and LAN drivewrs This disabled proper function of my PCI slot. Make sure u tell anyone who installed an ATI card on an NVIDA board NOT to Delete Nvidia Chipset drivers or LAN drivers only the Display Drivers. To aviod an unstable computer. Thanx everyone for the help !!!