Dual boot Win7 & XP separate drives, reinstall XP?


I have a Gateway PC suppllied with XP pro pre-installed and a hidden recovery partition.

Recently fitted a second hard drive and installed Windows 7 pro on it which was fine and I was able to boot to either system. Used EasyBCD and can see that boot drive is on the original disk.

My XP system has now got a bit messed up and as I use it for some applications that won't run on Win7 want to reinstall it. The problem I have is that when I try to carry out system restore by pressing function key after POST it initially seems to start but then goes to BSOD.

I am guessing that this is because the boot sector and MBR on drive 0 have been modified when installing Win7.

Is there any way I can restore my original XP system and still be able to boot into both XP and Win7.

Thanks for any help or suggestions.
Thanks for the reply but I really want to use Windows 7 as my main system and need to run XP occasionally for some applications which won't work on Win 7.
Thanks for the response.
Those instructions seem to apply if you cannot boot into any version of Windows. I am able to get into both XP and Win 7 but what I would like to do is a reinstall of XP.
I have 2 hard drives, the original one has XP and a hidden recovery partition. The second drive which I added later has Windows 7. If I try to get in to the Gateway system recovery using F11 on startup I get blue screen of death.