Win XP completely destroyed my mac

I set a partition of 20 gb and purchased Windows XP Pro. SP2. 10 min into the Windows installation the loading stops and a message in the blue screen appears and says:

"A problem has been detected and windows has been shut down to prevent further damage to your computer.

Session3 InstalizationFailed

If this is the first time you have seen this STOP error screen, restart the computer. If this happens again follow these steps.

Check to make sure that hardware and software are properly installed. If this is a new installation please ask your hardware or software manufacturer for any windows updates you might need

If the problem continues, Disable or Remove any newly installed hardware or software. Disable BIOS options such as cacheing or shadowing. If you need to use Safe mode to remove or disable components, restart your computer. Use F8 to select advanced startup options and the select safe mode

Tech. Information"

* STOP: 0X0000006F (0XC0000020, 0X00000000, 0X00000000, 0X00000000)

So i followed the instructions and did a hard boot. I turned it back on and after my mac started its regular booting up sequence with the grey screen a black screen appeared saying:

"No bootable device -- Insert boot disk and press any key

-"

i started pressing keys like crazy but the screen would not change. So i hard booted again without the XP disc and the same thing happened.
Then i used the Leopard disc and still the black screen came on. I tried all types of combinations with the XP and Leo disc (not at the same time of course) and i still could not load XP or access my Mac Drive.

Please!! can someone help me!