If you suspect a problem with the PCI cards - the first thing to do would be to remove them all. Unless one is the graphics card - leave this in. If it still won't boot, change the graphics card to a different slot.
Unplug the floppy drive completely (might as well eliminate that from the equation too). If things still don't work, remove the CD-ROM as well.
If you can't get it working with minimum hardware, then either your problem isn't hardware related, or its more serious that one would hope for.
Also, if you post again post as many details about your system as possible - version of windows, motherboard model, amount and type of RAM, type of processor, etc.