XP boot problems on dual boot i7 PC

I need XP because I'm using some old but valuable programs that will not work on anything newer. I also need Win7 to run more recent stuff. However, the problems in getting both working on my machine have been the makings of a nightmare!

Hardware: Asus P8Z77-P Pro, i7 3770k, 16Gb ram, 2 x Samsung 840EVO 250Mb SSDs (1 for XP, the other for Win7), 1 x WD 2Tb HD (for work files).

I had it all working briefly having installed the AHCI drivers for XP, but then a few hours later it all fell over. Currently, having reinstalled XP first and got that working I then tackled Win7 (which I knew would overwrite the XP bootup) but got into Win7 and installed and deployed successfully Easy BCD to provide a boot menu. This currently works fine, Win7 booting perfectly but when selected XP starts off OK, gets as far as the XP logo and then reboots back to the menu for selecting the Easy BCD menu.

Looked online where there are endless solutions (!!) but none have worked so far and I really don't want to have to reload everything yet again!

Tried using the XP Pro install disk but this gets as far as loading all the files and then up comes BSOD. . .

0x00000078 (0xF78D2524, 0xC0000034, 0x00000000, 0x00000000)

This happens whether the bios is set to AHCI or IDE mode. Then I connected only the SSD that carries XP but the same result. Using f8 to find the safe mode option results in the load proceeding to file acpitabl.dat, after which it stays there for about 2 secs and then reboots. So, the upshot is that I can't seem to get it to do anything except reboot itself!

When booting from the XP disk, is it failing because the boot menu is getting in the way and it's trying to install on "thin air" . . ? Just tried booting it from the disk with all the HDs disconnected and the BSOD comes up in exactly the same way, after the files have loaded, with the same numbers as above.

Any guidance on recovering XP would be much appreciated!