|"i just want to know if my pci-e frequency would go up"|
I honestly can't answer that for sure. My guess would be that if the board officially supports 1066MHz FSB & the mod converts your CPU from 800MHz to 1066MHz FSB, you *probably* won't have a problem. Personally, I wouldn't do it.
"and if it does, would it be safe for my HDD and my video card?"
If it did, neither your data nor your video card would be safe.