I cannot get my xp pc to boot, been doing this for about a week now. I have changed the power supply, cleared the bios, and removed the video card and reinstalled it. any ideas on what this can be? When it first gets power it will power on for about 5-6 secs then won't turn back on.
Thanks for any help!

Welcome to PCHF

Sounds like it may be a bit more serious. If you have checked all of the connections, make sure that your motherboard isn't "shorting" (connecting)with your PC case. Also, check all of your cards (PCI/AGP), memory and processor are all seated correctly. Check that your CPU fan is spinning. Also, go into the bios and check you temperatures are not excessively high.

I pulled all pci and agp cards, reseated the cpu and memory, The cpu fan is running, and pulled out the motherboard completly, pc does not stay on long enough for me to get into bios. any other ideas? or is it time to invest in a new motherboard? thanks for the help

Well they would be the tests I would carry out. The problem is that the issue may be with your motherbaord, CPU or RAM. Is there any way at all that you can get hold of other components to test this?