Repair XP Pro SP2

I've looked at http://michaelstevenstech.com/XPrepairinstall.htm and it
starts out saying :
"Boot the computer using the XP CD. You may need to change the boot order in
the system BIOS so the CD boots before the hard drive. Check your system
documentation for steps to access the BIOS and change the boot order".

I realize this qustion may be premature since I have not installed my new
motherboard, new processor and drivers. Will the bios screen pop up first to
select my boot order? If so, this question is moot.
Will my old XP activation code work since I have a new board and processor?