My American Megatrends BIOS is quite different being for a Dell PC - but BIOS in all it's forms (except UEFI) follows the same set of rules - it is just a matter of working slowly and writing down any and all changes you have made.
Looking at your BIOS, hit F9 key to load the default settings (factory default) and the F10 to save and exit.
Try a re-start and see what happens. I would say that if XP starts it will be dated 1 January 2007. (from your previous screen shots).
Re-boot again with F2 or F10 held down to put you back to the BIOS level. The hit F9 and see what options that screen will give you - time and date change - boot order (CD, Hard Disk, perhaps USB - set this to your primary hard disk, c:\.
On every option you will see a short explanation on the right hand side of the BIOS screen.
Now don't worry or panic, you really cannot damage anything by changing BIOS settings - there is always the option to re-set to the default values.
I would leave the following alone:-
Chipset
Power Management
Frequency/Voltage
Have searched for any links about your BIOS version - not much luck.
I think regard F9 as your safety net.
Should your BIOS settings return to normal/default and still no boot into XP - umm, perhaps the MBR may be damaged. The genuine XP install CD has a repair option which opens in a DOS like screen - type in fixboot and see what happens.
That is the trouble with all this communicating on the net about problems. If any of us could actually lay our hands on your PC I am sure that one of the forum members would have your system up and running in under a minute or so unless anyone had to go looking for loose cables etc.
Anyway, good luck.
Aunty Jack.