I am thinking about taking all of my hp slimline 5703w's components and putting them inside a bigger case such as a haf 922 or
an antec 300, but I am wondering if they all have the same power/reset headers, and would windows recognize it and would require me to install win 7 again?
the only time you need to reinstall windows or re register it with ms if you swapped out the mb, most vendors now use standed mb from standard mb vendors like asus. you can google your hp model to find the mb that hp used as a service part#. the vendor and modem and service part number is also silk screened onto your mb. the on/off/reset/hd led headers been commom for years on all mb vendors. a few years ago hp and other vendors would change the atx power header or use a non standard ps that forced you to buy the parts from them.
I've had excellent results moving HP & compaq's to standard cases. Usually the lower inner corner, where the front panel connectors are, doesn't have a screwhole for that standoff that will be there. Remove the standoff from the case or insulate it so it doesnt short out the motherbd.
as for if the front panel cables will fit or not is a toss up. sometimes they use normal plugs and sometimes they don't, If they dont you can figure how the new plugs fit in by comparing the old plugs and where they went.