Wanting to upgrade MB and CPU

No. You may have to format, reload windows, and re-activate it online. You'll also jeopardise your warranty. I recommend you just change the power supply and video card to start with, so you can restore your system to it's original self, in case you need the warranty later. Use cpuid, a free download, to id the motherboard and chipset. It might work with the 8500 without a bios flash. I found supported cpus for my compaq board clearly listed on hp's website. For more responses, I would list your system specs, including model number. Finally, check the back of the case for a removable backplate to determine if you have a standard micro atx board, which is what many oem systems have. Atx boards won't fit in micro atx cases.